Metals and Non-metals notes

Metals & Non-metals

Metals and non-metals are two broad classes of elements with distinct physical and chemical properties. Metals, such as iron, copper, and gold, are generally shiny, good conductors of heat and electricity, malleable, and ductile. They tend to lose electrons in chemical reactions, forming positive ions. Non-metals, like oxygen, sulfur, and carbon, usually have dull appearances, are poor conductors, and are brittle when solid. They tend to gain or share electrons during reactions, forming negative ions or covalent bonds. While metals are mostly found on the left side of the periodic table, non-metals are found on the right. These differences make them essential for a wide range of uses in daily life and industry.

Availability of Metals and Non-Metals in the Earth:

Metals and non-metals are both abundantly found in the Earth's crust but in different forms and distributions. Metals are generally found in the form of ores, which are minerals from which metals can be extracted profitably. Common metallic elements like aluminium, iron, copper, gold, and silver are extracted from bauxite, hematite, chalcopyrite, and other ores. Iron and aluminium are among the most abundant metals in the Earth's crust. On the other hand, non-metals like oxygen, silicon, carbon, sulphur, and nitrogen occur in both free and combined states. Oxygen is the most abundant non-metal and makes up nearly half of the Earth's crust, mostly in the form of oxides and silicates. Nitrogen dominates the Earth's atmosphere, forming about 78% by volume. Non-metals are crucial for life and are found in air, water, soil, and living organisms.

Classification of Elements: Metals, Non-Metals & Metalloids

Elements are broadly classified based on their physical and chemical properties. The three main categories are: Metals, Non-Metals, and Metalloids.

Metals

Shiny, hard solids (except mercury – liquid).
Good conductors of heat and electricity.
Malleable, ductile, and sonorous.
Examples: Iron (Fe), Copper (Cu), Zinc (Zn), Aluminium (Al)

Non-Metals

Dull appearance, brittle (not malleable).
Poor conductors of heat and electricity (except graphite).
Usually gases or soft solids.
Examples: Oxygen (O), Carbon (C), Nitrogen (N), Sulphur (S)

Metalloids

Have both metallic and non-metallic properties.
Semi-conductors: conduct electricity under certain conditions.
Used in electronics and solar cells.
Examples: Silicon (Si), Arsenic (As), Boron (B)

Comparison Table: Metals vs Non-Metals

Property	Metals	Non-Metals
Appearance	Shiny (lustrous)	Dull
Malleability	Malleable and ductile	Brittle
Conductivity	Good conductors	Poor conductors (except graphite)
Physical State	Mostly solids	Gases or brittle solids
Melting Point	High	Low (except diamond)
Examples	Fe, Cu, Al, Zn	O, C, N, Cl

Physical Properties of Metals:

Metals are a class of elements known for their distinctive physical characteristics, which make them essential in everyday life and various industries. Most metals are solid at room temperature, with the notable exception of mercury, which remains liquid. They exhibit a bright, shiny surface called metallic lustre which is seen clearly in metals like gold, silver, and aluminum when freshly polished. Metals are generally hard and strong; for example, iron and steel are used in construction due to their strength, while titanium is used in aircraft for its strength and light weight. However, some metals like sodium and potassium are soft and can be cut with a knife. Malleability is another key property, meaning metals can be hammered into thin sheets without breaking. Gold and silver are the most malleable metals and are used extensively in jewelry. Metals are also ductile, meaning they can be stretched into wires, such as copper wires used in electrical systems and aluminum wires in power transmission. Additionally, metals are excellent conductors of heat and electricity; copper and silver are the best conductors and are widely used in electrical appliances and circuits. They generally have high melting and boiling points; for example, tungsten has one of the highest melting points of all elements and is used in light bulb filaments. Most metals are dense and heavy, like lead, which is used in radiation shielding. Another characteristic is sonority , metals produce a ringing sound when struck, which is why bells are made from bronze (a metal alloy). These physical properties make metals indispensable in tools, transportation, electronics, construction, and decorative arts.

Chemical Properties of Metals:

Metals display a variety of chemical properties that distinguish them from non-metals. One of the most common reactions is with oxygen. Most metals react with oxygen to form metal oxides. For example, when magnesium burns in air, it forms magnesium oxide (MgO), a basic oxide. Similarly, iron reacts with oxygen and moisture over time to form rust (iron oxide), which is a major issue in the corrosion of bridges and tools. Metals also react with water, though the reactivity variesâ€”potassium and sodium react vigorously with cold water to produce their respective hydroxides and hydrogen gas, while calcium reacts slowly. Less reactive metals like iron and copper do not react easily with cold water, but may react with steam. Metals also react with acids like hydrochloric acid and sulfuric acid to produce salt and hydrogen gas. For instance, zinc reacts with hydrochloric acid to form zinc chloride and hydrogen gas. The general reaction is: Metal + Acid produces Salt + Hydrogen. Another key chemical property is displacement; more reactive metals can displace less reactive metals from their salt solutions. For example, if iron is placed in copper sulfate solution, it displaces copper and forms iron sulfate. This property is widely used in metallurgy and metal extraction processes. In addition, metals tend to lose electrons during chemical reactions, forming positive ions (cations), which is why they are known as electropositive elements. These chemical behaviors are fundamental in understanding metal reactivity, corrosion, metallurgy, and their applications in chemical industries.

Properties of Non-Metals:

Non-metals are elements that generally lack the characteristics of metals and are found on the right side of the periodic table (except hydrogen). They can exist in solid, liquid, or gaseous states at room temperature. For instance, oxygen and nitrogen are gases, bromine is a liquid, and sulfur and carbon are solids. Unlike metals, non-metals are poor conductors of heat and electricity, such as aseen in graphite (a form of carbon). Graphite is a notable exception as it conducts electricity. Non-metals are not lustrous and have a dull appearance; however, iodine is an exception as it has a shiny surface. They are brittle and break easily when solid, so they cannot be drawn into wires (non-ductile) or hammered into sheets (non-malleable). Non-metals have low melting and boiling points, though graphite again is an exception with a very high melting point. Chemically, non-metals tend to gain electrons during reactions, forming negative ions (anions), and are therefore electronegative. They often form acidic or neutral oxides, such as carbon dioxide (CO2) or nitrogen dioxide (NO2), unlike metals that form basic oxides. Non-metals also react with hydrogen to form covalent hydrides like ammonia (NH3) and methane (CH4). Examples of common non-metals include carbon, sulfur, phosphorus, nitrogen, oxygen, and chlorine. These elements play vital roles in biological systems, industrial processes, and environmental cycles.

Comparison Table: Metals vs Non-Metals

Property	Metals	Non-Metals
Reaction with Oxygen	Form basic oxides	Form acidic or neutral oxides
Reaction with Water	Produce metal hydroxides and hydrogen gas	Generally do not react with water
Reaction with Acids	Release hydrogen gas	Typically do not react with acids

Type	Element Name	Symbol	Appearance	Key Properties	Common Uses
Metals	Iron	Fe	Grey, shiny when polished	Strong, magnetic, malleable, rusts in moist air	Construction, machinery, bridges, vehicles
	Copper	Cu	Reddish-brown	Excellent conductor	Electrical wires, coins
	Aluminium	Al	Silvery-white	Lightweight, corrosion-resistant	Aircraft, utensils
	Gold	Au	Yellow, shiny	Malleable, doesn’t tarnish	Jewellery, electronics
	Silver	Ag	White, shiny	Best conductor	Jewellery, photography
	Zinc	Zn	Blue-white	Alloy use, corrosion-resistant	Galvanizing, batteries
	Lead	Pb	Grey, heavy	Soft, dense	Radiation shields, batteries
	Mercury	Hg	Liquid	Only liquid metal	Thermometers, barometers
	Nickel	Ni	Silver-white	Magnetic, corrosion-resistant	Coins, batteries
	Chromium	Cr	Shiny grey	Hard, lustrous	Stainless steel, plating
Non-Metals	Oxygen	O	Colorless gas	Essential for life	Breathing, combustion
	Hydrogen	H	Colorless gas	Lightest element	Fuel cells, ammonia
	Carbon	C	Black/Diamond	Allotropes, base of life	Coal, graphite, diamond
	Nitrogen	N	Colorless gas	Inert, 78% air	Fertilizers, cryogenics
	Phosphorus	P	Red/white	Reactive, essential	Fertilizers, detergents
	Sulfur	S	Yellow solid	Smelly gas, burns blue	Rubber, sulfuric acid
	Chlorine	Cl	Green gas	Toxic, disinfectant	Water treatment, bleach
	Fluorine	F	Yellow gas	Highly reactive	Toothpaste, Teflon
	Iodine	I	Violet solid	Antiseptic, vapor	Medicine, disinfectants
	Bromine	Br	Red-brown liquid	Toxic, volatile	Flame retardants

Properties of Metals vs Non-Metals - Summary

Property	Metals	Non-Metals
Appearance	Lustrous (shiny)	Usually dull
Conductivity	Good conductors of heat and electricity	Poor conductors
Malleability	Malleable and ductile	Brittle (if solid)
Density	High	Low (generally)
State at Room Temp	Solid (except mercury)	Solid, liquid, or gas
Melting/Boiling Points	Usually high	Usually low
Sonority	Sonorous (makes sound when hit)	Non-sonorous

Appearance Metals are generally shiny and have a metallic lustre. Example: Gold, Silver, and Copper. Non-metals usually have a dull appearance and lack shine. Exception: Iodine appears shiny. Physical State Almost all metals are solid at room temperature. Exception: Mercury is a liquid metal. Non-metals may exist as solids (sulphur), liquids (bromine), or gases (oxygen, nitrogen). Hardness Most metals are hard and strong (e.g., iron). However, sodium and potassium are soft and can be cut with a knife. Non-metals are generally brittle in solid form and not hard. Exception: Diamond, a form of carbon, is extremely hard. Malleability Metals can be hammered into thin sheets (malleable). Example: Aluminium foil. Non-metals are non-malleable and break easily when hammered. Ductility Metals can be drawn into wires. Example: Copper wires used in electrical wiring. Non-metals are not ductile and break when stretched. Conductivity Metals are good conductors of heat and electricity. Silver and copper are among the best conductors. Most non-metals are poor conductors. Exception: Graphite conducts electricity due to free electrons. Melting & Boiling Points Metals have high melting and boiling points. Example: Tungsten has the highest melting point among metals. Non-metals generally have lower melting and boiling points. Exception: Diamond has a very high melting point. Density Metals usually have high density and are heavy. Example: Lead is very dense. Non-metals often have low density and are lighter. Example: Hydrogen and helium are light gases. Sonority Metals produce a ringing sound when struck and are sonorous. Example: School bells made of metal. Non-metals are non-sonorous and do not produce a ringing sound when struck. Chemical Reactivity Metals tend to lose electrons and form positive ions (cations) during chemical reactions. They react with acids to produce hydrogen gas. Non-metals tend to gain or share electrons to form negative ions (anions) or covalent bonds. They do not react with acids in general. Oxide Nature Metals form basic oxides when they react with oxygen. Example: Magnesium forms magnesium oxide (MgO). Non-metals form acidic or neutral oxides. Example: Sulphur dioxide (SO2) is an acidic oxide. Examples Iron (Fe), Copper (Cu), Aluminium (Al), Silver (Ag), Zinc (Zn) Oxygen (O), Carbon (C), Sulphur (S), Phosphorus (P), Chlorine (Cl)

Reaction of Metals

Reactant	General Reaction	Example Equation	Detailed Explanation
Metals + Oxygen	Metal + O₂ → Metal Oxide	4Al + 3O₂ → 2Al₂O₃ 2Mg + O₂ → 2MgO	Metals react with oxygen to form metal oxides. These oxides are generally basic in nature. Some, like aluminium oxide, are amphoteric. Highly reactive metals (e.g., potassium, sodium) ignite spontaneously in air, while less reactive ones (e.g., gold, silver) do not react easily.
Metals + Acids	Metal + Dilute Acid → Salt + H₂	Zn + 2HCl → ZnCl₂ + H₂ Mg + H₂SO₄ → MgSO₄ + H₂	Metals above hydrogen in the reactivity series displace hydrogen from dilute acids, producing a salt and hydrogen gas. Unreactive metals like copper, silver, and gold do not react with dilute acids.
Metals + Bases	Metal + Alkali (Strong base) → Complex Salt + H₂	Zn + 2NaOH → Na₂ZnO₂ + H₂ Al + NaOH → NaAlO₂ + H₂	Amphoteric metals like zinc and aluminium react with strong bases (e.g., NaOH) to form complex salts like sodium zincate or sodium aluminate along with hydrogen gas. This reaction is specific to amphoteric behavior.
Metals + Non-Metals	Metal + Non-metal → Ionic Compound	2Na + Cl₂ → 2NaCl Mg + Br₂ → MgBr₂	Metals react with non-metals (especially halogens) to form ionic compounds. Metals lose electrons to form cations while non-metals gain electrons to form anions. The result is a stable ionic bond in compounds like sodium chloride.
Metals + Salt Solutions	Metal A + Salt (of B) → Salt (of A) + Metal B	Fe + CuSO₄ → FeSO₄ + Cu Zn + Pb(NO₃)₂ → Zn(NO₃)₂ + Pb	A more reactive metal displaces a less reactive metal from its salt solution. This single displacement reaction depends on the metal's position in the reactivity series. It's used for metal extraction and purification.
Metals + Water	Metal + Cold Water → Metal Hydroxide + H₂ Metal + Steam → Metal Oxide + H₂	2Na + 2H₂O → 2NaOH + H₂ Zn + H₂O (steam) → ZnO + H₂	Highly reactive metals (K, Na, Ca) react violently with cold water. Moderately reactive metals (Mg, Zn) react only with hot water or steam. Unreactive metals like Cu, Ag don’t react with water at all.
Metals + Hydrogen	Metal + H₂ (at high temp) → Metal Hydride	2Li + H₂ → 2LiH Ca + H₂ → CaH₂	Reactive alkali and alkaline earth metals form ionic metal hydrides at elevated temperatures. These hydrides are often used in hydrogen storage, desiccants, or reducing agents in chemistry.
Metals + CO₂	Metal + CO₂ → Metal Oxide + C	4Al + 3CO₂ → 2Al₂O₃ + 3C 3Mg + CO₂ → 3MgO + C	At very high temperatures, reactive metals like Al and Mg can reduce carbon dioxide to carbon. These are redox reactions where the metal is oxidized and CO₂ is reduced. This is used in thermite-type reactions and pyrotechnics.

Reactions of Non-Metals

Non-metals exhibit diverse chemical behavior when reacting with different substances. Unlike metals, they tend to gain electrons and form covalent or ionic compounds. The flowchart below summarizes their major reactions:

Reaction with Oxygen
Non-metals form acidic oxides.
e.g., C + O₂ → CO₂

Reaction with Water
Generally do not react.
Chlorine dissolves to form HCl & HOCl

Reaction with Hydrogen
Forms covalent hydrides.
e.g., N₂ + 3H₂ → 2NH₃

Reaction with Acids
No significant reaction.
Non-metals do not displace H₂ gas.

Reaction with Bases
Some react with alkali to form salts.
e.g., Cl₂ + NaOH → NaCl + NaOCl

Reaction with Salts
More reactive non-metals displace less reactive ones.
Cl₂ + KBr → KCl + Br₂

Reaction with Metals
Forms ionic compounds.
e.g., Na + Cl → NaCl

Ionic compounds

Ionic compounds are the compounds formed by the transfer of electrons from a metal to a non-metal are called ionic compounds or electrovalent compounds.

Properties of Ionic Compounds

Physical nature: They are solid and hard, generally brittle.

Melting and Boiling Poi: ntThey have high melting and boiling point.

Solubility : Generally soluble in water and insoluble in solvents such as kerosene, petrol etc.

Reactivity Series

The Reactivity Series of Metals is a list of metals arranged in the order of their chemical reactivity. This series helps us predict how metals will behave in various chemical reactions, including their reactions with water, acids, oxygen, and other substances. Highly reactive metals are placed at the top and react quickly, even explosively, while less reactive or noble metals are at the bottom and do not react easily. Understanding the reactivity series is essential for processes like extraction of metals, displacement reactions, corrosion control, and industrial applications.

Position	Metal	Reacts with Water	Reacts with Acids	Tendency to Lose Electrons	Remarks/Uses
1	Potassium (K)	Violently with cold water	Instantly	Very high	Stored in kerosene; highly explosive
2	Sodium (Na)	Violently with cold water	Instantly	Very high	Used in street lights and chemical synthesis
3	Calcium (Ca)	Slowly with cold water	Vigorously	High	Essential in bones and cement
4	Magnesium (Mg)	With hot water/steam	Vigorously	High	Used in alloys, fireworks, and medicine
5	Aluminium (Al)	Only with steam	Reactively	Moderate	Used in aircraft, utensils; amphoteric
6	Zinc (Zn)	With steam	Vigorously	Moderate	Galvanization; forms zinc oxide
7	Iron (Fe)	With steam	Slowly	Moderate	Construction and tools
8	Lead (Pb)	No reaction	Slowly	Low	Battery plates; toxic in nature
9	Hydrogen (Reference)	—	—	—	Used as a benchmark in the series
10	Copper (Cu)	No reaction	Does not react	Very low	Wires, utensils; used in coinage
11	Mercury (Hg)	No reaction	No reaction	Very low	Thermometers; toxic metal
12	Silver (Ag)	No reaction	No reaction	Very low	Jewellery, coins; antimicrobial
13	Gold (Au)	No reaction	No reaction	Extremely low	Highly unreactive; used in electronics & ornaments
14	Platinum (Pt)	No reaction	No reaction	Lowest	Noble metal; catalyst in chemical reactions

Extraction of Metals – Step-by-Step Explanation

Metals are extracted from their natural mineral sources (ores) through a series of steps involving both physical and chemical processes. The method of extraction depends on the metal's reactivity and the nature of its ore. The entire process can be divided into four major steps, as shown below:

Metal Extraction Phases

1. Concentration of Ore
Physical removal of impurities (gangue) from the ore.

→

2. Conversion to Oxide
Roasting or calcination depending on the nature of the ore.

→

3. Reduction of Oxide
Using carbon, CO, or electricity to extract metal.

→

4. Refining of Metal
Refining of metals refers to the removing impurities from crude metal.

Step 1: Concentration of Ore

Ores are found mixed with sand, clay, and unwanted minerals called gangue. Concentration removes these impurities to increase the percentage of metal in the ore. Common methods:

Gravity Separation: Heavier ore particles are separated using water (used for oxide ores).
Froth Flotation: Sulphide ores are treated with oil and air; ore attaches to bubbles and rises while gangue sinks.
Magnetic Separation: Used when one component is magnetic (e.g., magnetite vs. non-magnetic gangue).

Step 2: Conversion to Metal Oxide

Ores are converted into oxides because they are easier to reduce. This step depends on the ore type:

Roasting: Sulphide ores are heated in presence of air (O₂) to form oxides.
Example: 2ZnS + 3O₂ → 2ZnO + 2SO₂
Calcination: Carbonates and hydrated ores are heated in the absence of air.
Example: ZnCO₃ → ZnO + CO₂

Step 3: Reduction of Metal Oxide

Metal oxides are reduced to free metals. The process depends on the reactivity of the metal:

Low reactive metals (e.g., Hg, Cu): Heated directly in air to obtain metal.
Moderate reactive metals (e.g., Fe, Zn, Pb): Reduced using carbon (C) or carbon monoxide (CO).
Example: Fe₂O₃ + 3CO → 2Fe + 3CO₂
Highly reactive metals (e.g., Na, K, Al): Extracted by electrolysis of molten salts.
Example: Electrolysis of molten NaCl → Na + Cl₂

Step 4: Refining of Crude Metal

The metal obtained from reduction is impure and needs to be purified before use:

Electrolytic Refining: Most common method. Impure metal is the anode; pure metal forms at the cathode.
Used for: Cu, Zn, Ag, Au
Distillation: For low boiling point metals like zinc and mercury.
Liquation: Metal with low melting point is melted and separated from impurities.

Summary Table: Methods Based on Metal Reactivity

Reactivity	Examples	Extraction Method
High	Sodium, Potassium, Calcium, Aluminium	Electrolysis of molten chlorides/oxides
Moderate	Iron, Zinc, Lead	Reduction using carbon or CO
Low	Mercury, Copper, Silver, Gold	Roasting and direct reduction

How Are Alloys Made? – Flowchart

The formation of alloys is a stepwise process involving the mixing of metals and sometimes non-metals to improve material properties. Below is a color-coded, interactive guide to the alloying process:

Step 1: Select Base Metal

Choose the primary metal such as iron, copper, or aluminium as the foundation of the alloy.

Step 2: Choose Alloying Element

Select one or more other elements (metals or non-metals) to mix with the base metal to enhance specific properties.

Step 3: Melt the Components

Heat the metals until they melt and mix thoroughly to form a uniform liquid solution.

Step 4: Cool and Solidify

Let the molten mixture cool and crystallize into a solid alloy with enhanced mechanical and chemical properties.

Step 5: Shape and Use

The alloy is cast or rolled into useful forms for industries like construction, aerospace, electronics, and jewellery.

Ionic and Non-Ionic (Covalent) Compounds

Compounds are formed when atoms combine chemically. Based on how they bond, compounds are categorized as: Ionic Compounds (formed by transfer of electrons) and Covalent Compounds (formed by sharing of electrons).

Infographic: How Do Bonds Form?

Ionic Bond Formation

Occurs between metal and non-metal
Metal loses electrons → Cation
Non-metal gains electrons → Anion
Opposite ions attract electrostatically

Example: Na + Cl → Na⁺ + Cl⁻ → NaCl

Covalent Bond Formation

The nature of bonding in a compound determines its structure, properties, and uses. Ionic compounds are strong, high-melting, and conductive in molten form. Covalent compounds are mostly gases or liquids, with lower melting points and limited conductivity. Both types are essential to life and industry.

Occurs between two non-metals
Atoms share electrons to complete octet
Forms molecules, not ions
Bonds are directional and specific

Example: H + H → H₂ (shared pair)

Comparison Between Ionic and Covalent Compounds

Property	Ionic Compounds	Covalent Compounds
Bond Type	Transfer of electrons (Ionic Bond)	Sharing of electrons (Covalent Bond)
Elements Involved	Metal + Non-metal	Non-metal + Non-metal
Conductivity	Conducts in molten/solution state	Does not conduct electricity
Physical State	Usually solids (crystalline)	Usually gases or liquids
Melting/Boiling Point	High	Low to moderate
Examples	NaCl, KBr, MgO	H₂O, CO₂, CH₄

Corrosion

The surface of some metals loses which lead to dull appearance is called corrosion. The loss of surface is due to the exposure of a metal to moist air for a long period of time.

Some examples of corossion are:

Iron when exposed to moist air acquires a coating of a brown flaky substance called rust.
Silver becomes black when exposed to air as it reacts with air to form a coating of silver sulphide.
Copper reacts with moist carbon dioxide in the air and gains a green coat of copper carbonate.

Prevention of Corrosion
The rusting of iron can be prevented by painting, oiling, greasing, galvanizing, chrome plating, anodizing or making alloys. The most common methods of prevention are galvanization and alloy.

Galvanization : It is a method of protecting steel and iron from rusting by coating them with a thin layer of zinc.

Making an alloy : An alloy is a homogeneous mixture of two or more metals or a metal and a non- metal.

Examples of alloy:

Iron : Mixed with small amount of carbon becomes hard and strong.
Steel : Iron + Nickel and chromium
Brass : Copper + Zinc
Bronze : Copper + Tin (S)
Solder : Lead + tin
Amalgam : If one of the metal is mercury (Hg)

Different Methods of Corrosion Prevention

Method	Process	Example / Use
Painting	Creating a physical barrier to prevent moisture and oxygen contact	Iron gates, machinery
Greasing / Oiling	Applying grease or oil to create a water-repellent layer	Tools, machine parts
Galvanization	Coating the surface with a layer of zinc which corrodes instead of the base metal	Water pipes, guard rails
Electroplating	Depositing a layer of metal like chromium or nickel using electrolysis	Car parts, kitchen utensils
Alloying	Mixing a metal with one or more other elements to improve corrosion resistance	Stainless steel (iron + chromium + nickel)
Cathodic Protection	Attaching a more reactive metal (sacrificial anode) to protect the main metal	Ship hulls, underground pipelines
Anodizing	Forming a thick oxide layer on the metal surface through electrochemical oxidation	Aluminium utensils, aircraft parts

Textbook Question Answers

1. Give an example of a metal which:

is a liquid at room temperature
can be easily cut with a knife
is the best conductor of heat
is a poor conductor of heat

Answer:

Mercury is the metal which is liquid at room temperature.
Sodium and potassium are the metals which can be cut with a knife.
Silver is the best conductor of heat.
Mercury and lead are poor conductors of heat.

2. Explain the meanings of malleable and ductile.

Answer:

Malleable: Metals that can be beaten into thin sheets.
Ductile: Metals that can be drawn into thin wires.

In-text Questions – Set 2

Why is sodium kept immersed in kerosene oil?

Answer: Sodium is a very reactive metal. It reacts quickly with oxygen and moisture in the air and may catch fire. To prevent this, it is stored in kerosene oil.
Write equations for the reactions of:
1. Iron with steam
2. Calcium and potassium with water
Answer:
1. Iron reacts with steam to form a magnetic oxide of iron and hydrogen gas:
  3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)
2. Calcium reacts with water to form calcium hydroxide and hydrogen:
  Ca(s) + 2H₂O(l) → Ca(OH)₂(aq) + H₂(g)
  
  Potassium reacts violently with water, producing potassium hydroxide and hydrogen gas:
  2K(s) + 2H₂O(l) → 2KOH(aq) + H₂(g)

3. Reactivity of Metals (Displacement Reactions)

Samples of four metals A, B, C, and D were tested with different salt solutions. The table below records their reactivity based on displacement reactions:

Metal	Iron(II) Sulphate	Copper(II) Sulphate	Zinc Sulphate	Silver Nitrate
A	No reaction	Displacement	–	–
B	Displacement	–	–	–
C	No reaction	No reaction	No reaction	Displacement
D	No reaction	No reaction	No reaction	No reaction

Conclusion:
From the displacement reactions, the reactivity order is:
B > A > C > D

Answer the following:

Which is the most reactive metal?
Metal B is the most reactive as it gives a displacement reaction with Iron(II) sulphate.
What would you observe if B is added to a solution of Copper(II) sulphate?
When metal B is added to copper(II) sulphate solution, a displacement reaction takes place. The blue colour of copper(II) sulphate solution fades, and a reddish-brown deposit of copper forms on metal B.
Arrange the metals A, B, C and D in the order of decreasing reactivity.
Metal B is the most reactive as it displaces iron from its salt solution. Metal A is less reactive as it displaces copper from its salt solution. Metal C is still less reactive as it can displace only silver from its salt solution. Metal D is the least reactive as it does not displace any metal.
Order of decreasing reactivity: B > A > C > D

4. Which gas is produced when dilute hydrochloric acid is added to a reactive metal?

Answer:

Hydrogen gas is liberated when dilute hydrochloric acid is added to a reactive metal.

Example:
When iron reacts with dilute sulphuric acid:
Fe(s) + H₂SO₄(aq) → FeSO₄(aq) + H₂(g)

5. What would you observe when zinc is added to a solution of iron(II) sulphate?

Answer:

Zinc is more reactive (more electropositive) than iron. Therefore, zinc displaces iron from its salt solution. The pale green colour of ferrous sulphate turns colourless as zinc sulphate forms.

Chemical Reaction:
FeSO₄(aq) + Zn(s) → ZnSO₄(aq) + Fe(s)
(Ferrous sulphate – light green; Zinc sulphate – colourless)

In-text Questions – Set 3

1. (i) Write the electron-dot structures for sodium and oxygen.
(ii) Show the formation of Na₂O and MgO by the transfer of electrons.
(iii) What are the ions present in these compounds?

Answer:

(i) Electron-dot structures:

Sodium (Na): Na •
Oxygen (O): ••O••

(ii) Formation of compounds:

Formation of Magnesium Oxide (MgO):
When magnesium reacts with oxygen, the magnesium atom transfers its two outermost electrons to an oxygen atom. By losing two electrons, the magnesium atom forms a magnesium ion (Mg²⁺), and by gaining two electrons, the oxygen atom forms an oxide ion (O²⁻).

Mg + O → MgO

Formation of Sodium Oxide (Na₂O):
Two sodium atoms each transfer one electron to an oxygen atom. By losing these electrons, sodium forms sodium ions (Na⁺), and the oxygen atom forms an oxide ion (O²⁻).

2Na + O → Na₂O

(iii) Ions present:

In sodium oxide (Na₂O): 2Na⁺ and O²⁻
In magnesium oxide (MgO): Mg²⁺ and O²⁻

2. Why do ionic compounds have high melting points?

Answer: Ionic compounds contain strong electrostatic forces of attraction between oppositely charged ions (positive and negative). A large amount of heat energy is required to overcome these forces, so ionic compounds have high melting points.

In-text Questions – Set 4

1. Define the following terms:

(i) Mineral: Minerals are naturally occurring compounds found in the Earth’s crust. Example: Alum (K₂SO₄.Al₂(SO₄)₃.24H₂O).

(ii) Ore: Ores are minerals from which metals can be extracted profitably. Example: Bauxite (Al₂O₃.2H₂O) is the ore of aluminium.

(iii) Gangue: The impurities such as sand and rocky materials that are mixed with ores are called gangue.

2. Name two metals which are found in nature in the free state.

Answer: Gold and Platinum.

3. What chemical process is used for obtaining a metal from its oxide?

Answer: The reduction process is used to obtain a metal from its oxide.

Examples:

ZnO + C → Zn + CO

PbO + C → Pb + CO

In-text Questions – Set 5

1. Metallic oxides of zinc, magnesium, and copper were heated with the following metals.

Metal	Zinc	Magnesium	Copper
Zinc Oxide	–	Displacement	–
Magnesium Oxide	–	–	–
Copper Oxide	Displacement	Displacement	–

Explanation: A more reactive metal can displace a less reactive metal from its oxide. Among zinc, magnesium, and copper, magnesium is the most reactive and copper is the least reactive.

2. Which metals do not corrode easily?

Answer: Gold and Platinum do not corrode easily.

3. What are alloys?

Answer: An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal. Examples: Brass (Copper + Zinc), Bronze (Copper + Tin).

Exercise Questions – Metals and Non-Metals

1. Which of the following pairs will give displacement reactions?

NaCl solution and copper metal
MgCl₂ solution and aluminium metal
FeSO₄ solution and silver metal
AgNO₃ solution and copper metal

Answer: (d) AgNO₃ solution and copper metal.

Copper displaces silver from silver nitrate solution. Silver metal is deposited and copper(II) nitrate is formed.

Chemical Equation:
Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq) + 2Ag(s)

2. Which of the following methods is suitable for preventing an iron frying pan from rusting?

Applying grease
Applying paint
Applying a coating of zinc
All of the above

Answer: (c) Applying a coating of zinc.

Although grease or paint can prevent rusting, they cannot be used on a frying pan. Galvanizing (coating with zinc) is the most suitable method.

3. An element reacts with oxygen to give a compound with a high melting point, which is soluble in water. The element is likely to be:

Calcium
Carbon
Silicon
Iron

Answer: (a) Calcium.

Calcium reacts with oxygen to form calcium oxide (CaO), which has a high melting point and is soluble in water to form calcium hydroxide.

Ca + O₂ → CaO
CaO + H₂O → Ca(OH)₂

4. Food cans are coated with tin and not with zinc because

Zinc is costlier than tin.
Zinc has a higher melting point than tin.
Zinc is more reactive than tin.
Zinc is less reactive than tin.

Answer: (c) Zinc is more reactive than tin.

If zinc were used, it could react with food substances due to its higher reactivity.

5. You are given a hammer, a battery, a bulb, wires and a switch.

(a) How could you use them to distinguish between samples of metals and non-metals?
(b) Assess the usefulness of these tests in distinguishing between metals and non-metals.

Answer:

Malleability test: Metals can be beaten into sheets using a hammer, while non-metals break into pieces.
Conductivity test: Metals allow electric current to pass and make the bulb glow, while non-metals do not conduct electricity.
These tests help demonstrate malleability and electrical conductivity of metals and non-metals effectively.

6. What are amphoteric oxides? Give two examples.

Answer: Oxides that react with both acids and bases to form salt and water are called amphoteric oxides.

Examples: Lead oxide (PbO) and Aluminium oxide (Al₂O₃).

7. Name two metals which will displace hydrogen from dilute acids, and two metals which will not.

Answer:

Metals that displace hydrogen: Zinc (Zn), Magnesium (Mg)
Metals that do not displace hydrogen: Gold (Au), Silver (Ag)

8. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Answer:

Anode: Impure metal M
Cathode: Pure thin strip of metal M
Electrolyte: A solution of a salt of metal M

9. Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it.

(a) What will be the action of gas on:

Dry litmus paper
Moist litmus paper

(b) Write the balanced chemical equations.

Answer:

When sulphur is burnt in air, sulphur dioxide (SO₂) gas is formed.
(i) SO₂ has no effect on dry litmus paper.
(ii) SO₂ turns moist blue litmus paper red because it forms sulphurous acid (H₂SO₃) with water.

Equations:
S(s) + O₂(g) → SO₂(g)
SO₂(g) + H₂O → H₂SO₃(aq)

10. State two ways to prevent rusting of iron.

Answer:

By coating the surface of iron with rust-proof paint.
By applying oil or grease to prevent contact with air and moisture.

11. What type of oxides are formed when non-metals combine with oxygen?

Answer: Non-metals form acidic or neutral oxides with oxygen.

Examples: N₂O₅ (acidic oxide), CO (neutral oxide)

12. Give reasons:

Platinum, gold and silver are used to make jewellery.
Sodium, potassium and lithium are stored under oil.
Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

Answer:

These metals are highly lustrous, ductile, and malleable. They are also very less reactive and resist corrosion.
These metals react vigorously with water. To prevent contact with moisture, they are stored under oil.
Aluminium forms a protective oxide layer (Al₂O₃) that prevents further reaction, making it safe for cooking utensils.
It is easier to obtain metals from oxides by reduction than from carbonates or sulphides, so ores are first converted to oxides.

13. You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective.

Answer: Lemon and tamarind contain acids which dissolve the basic copper carbonate or copper oxide layer on the surface of tarnished vessels, restoring their bright reddish-brown shine.

14. Differentiate between Metals and Non-Metals on the basis of their Chemical Properties.

Metals	Non-Metals
When metals are heated with oxygen, they form ionic oxides which are basic in nature and form bases on dissolving in water. These turn red litmus paper blue.	When non-metals are heated with oxygen, they form covalent oxides which are acidic in nature. These form acids on dissolving in water and turn blue litmus paper red.
They are electropositive, lose electrons readily and form positive ions.	They are electronegative, gain electrons and form negative ions.
Metals are lustrous (shiny).	Non-metals are non-lustrous; graphite is an exception.
They act as reducing agents.	They act as good oxidising agents.
Metals are good conductors of heat and electricity.	Non-metals are poor conductors of heat and electricity; graphite is an exception.
All metals are solids except mercury.	Non-metals may exist in solid, liquid, or gaseous states.

15. A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?

Answer: The man used a solution called Aqua regia (Latin for “royal water”), which is a mixture of concentrated hydrochloric acid and concentrated nitric acid in a 3:1 ratio. Aqua regia can dissolve noble metals such as gold and platinum. When the upper layer of dull gold ornament dissolves, the bangles appear shiny but lose some weight.

16. Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).

Answer:
Copper is used for hot water tanks because it does not react with water or steam. Steel (an alloy of iron) reacts with steam and corrodes, making it unsuitable for this purpose.

Board exam papers- solutions

MCQs (multiple choice)

The amphoteric oxide among the following is
A) Potassium oxide B) Sodium oxide C) Calcium oxide D) Zinc oxide

Answer: D) Zinc oxide (Zinc oxide is amphoteric, meaning it can act both as an acid and a base, whereas the other oxides listed are not amphoteric.)

Brass, German silver and Gunmetal are the alloys of copper. Apart from copper the other commonmetal in them is

(A) zinc (B) tin (C) iron (D) nickel

Answer: A) Zinc (Brass is an alloy of copper and zinc, German silver is copper, zinc, and nickel, and Gunmetal is copper, tin, and zinc. The common metal in brass is zinc.)

You are required to arrange Fe, Zn and Mg in the increasing order of their reactivity. The correct arrangement is

(A) Mg, Zn, Fe (B) Fe, Mg, Zn (C) Fe, Zn, Mg (D) Zn, Mg, Fe.

Answer: A) Mg, Zn, Fe( Magnesium (Mg) is more reactive than zinc (Zn), and zinc is more reactive than iron (Fe).)

The alloy that contains copper and zinc as its constituents, is

(A) Brass (B) bronze C) German silver (D) gunmetal.

Answer: A) Brass (Brass is an alloy made primarily of copper and zinc.)

The reducing agent used in the extraction of silicon is

(A) Magnesium (B) Silica (C) Phosphorus (D) Sulphur.

Answer: A. Magnesium

The electronic configuration of element X is 2, 8, 8, 1 and the electronic configuration of element Y is 2, 8, 7. Then the type of bond formed between these two elements is

(A) covalent (B) hydrogen bond (C) metallic bond (D) ionic bond

Answer: D) Ionic bond (Element X has one electron in its outer shell (likely sodium) and element Y has seven (likely chlorine), so they form an ionic bond by transferring electrons.)

A group that has amphoteric oxides among the following is

(A) Sodium oxide and Copper oxide (B) Aluminium oxide and Zinc oxide

Answer: B) Aluminium oxide and Zinc oxide (Both aluminium oxide (Al₂O₃) and zinc oxide (ZnO) are amphoteric.)

The product produced when calcium oxide reacts with water.

(A) Slaked Lime (B) Gypsum (C) POP (D)Soda

Answer: A) Slaked Lime ( Calcium oxide reacts with water to form slaked lime (Ca(OH)₂).)

Sodium metal kept immersed in kerosene oil, because
It is highly reactive and reacts vigorously with air and water.
It is stored to protect it from light.
It is kept to prevent it from rusting.
It is used as a fuel

Answer: A) It is highly reactive and reacts vigorously with air and water.(Sodium metal reacts violently with air and water, so it is kept in kerosene oil to prevent such reactions.)

The metal added to iron to produce stainless steel?
Zinc b) Copper c) Nickel d) Aluminium

Answer: C) Nickel (Nickel is added to iron to make stainless steel, providing resistance to corrosion and enhancing strength)

Which property of metals is used for making bells and strings of musical instruments like Sitar and Violin?

(a) Malleability (b) Sonorousness (c) Ductility (d) Conductivity

Answer: B) Sonorousness( Metals are sonorous, meaning they produce a ringing sound when struck, making them ideal for musical instruments.)

The process in which a carbonate ore is heated strongly in the absence of air to convert it into metal oxide is called

(a) Roasting b) Calcination (c) Reduction (d) Smelting

Answer: B) Calcination (Calcination is the process of heating a carbonate ore in the absence of air to convert it to an oxide.)

Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?

(i) Au (ii) Ca (iii) Na (iv) K

(a) (i) and (ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (iii)and (iv)

Answer: B) (i) and (iii) (Au and Ca). Gold (Au) and calcium (Ca) can be refined by electrolytic refining.

2 & 4 Marks Questions

Q1: Aluminium is used for making cooking utensils. Which of the following properties of aluminium areresponsible for the same?

(i) Good thermal conductivity (ii) Good electrical conductivity (iii) Ductility (iv) High melting point

(a) (i) and (ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (i) and (iv)

Answer: (d) (i) and (iv)

Explanation: Aluminum is ductile and has a high electrical conductivity, which makes it unsuitable for utensil production. Aluminium has a high melting point and good heat conductivity. Copper, steel (an alloy of iron), and aluminium are the most popular metals used to make utensils. Due to their ability to conduct heat, copper and aluminium are the most used materials.

Q2: Which property of metals is used for making bells and strings of musical instruments like Sitar andViolin?

(a) Malleability (b) Sonorousness (c) Ductility (d) Conductivity

Answer: (b) Sonorousness

Explanation: Metal’s sonorousness refers to its ability to produce sound. As a result, it’s used to make musical instruments like the Sitar and the Violin’s bells and strings.

Q3: Due to their semiconductor properties the non-metals used in computers, T.V. etc. are

(a) Carbon (b) Bromine (c) Silicon (d) Fluorine

Answer: (c) Silicon

Explanation: Semiconductors are materials that have neither the conductivity of a conductor nor the insulating properties of an insulator. They are formed of pure silicon crystal, which is effectively pure silicon. Silicon is ideal for this lattice structure because its four valence electrons enable it to form perfect bonds with four of its silicon neighbours.

As a result, C is the correct answer.

Q4: Al₂O₃ + 2NaOH →_____ + H₂O

(a) Al(OH)₃ (b) Na₂O (c) NaAlO₂ (d) AlNaO₂

Answer: (c) NaAlO₂

Explanation: Alumina, or dialuminum trioxide, is the chemical formula for Al2O3. It’s a Lewis acid, to be precise.

Sodium hydroxide is abbreviated as NaOH. It’s a solid base. When a base reacts with an acid, the results are usually salt and water.

As a result, lewis acid alumina combines with the base sodium hydroxide to generate salt and water in this reaction.

Q5: Which of the following pairs will give displacement reactions?

(a) FeSO₄ solution and Copper metal

(b) AgNO₃ solution and Copper metal

(d) NaCl solution and Copper metal

Answer: (b) AgNO₃ solution and Copper metal

Explanation: The displacement reaction occurs when copper metal and silver nitrate solution are combined, and the chemical equation is: Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag.

Q6: Non-metals form covalent chlorides because

(a) they can give electrons to chlorine

(b) they can share electrons with chlorine

(d) they cannot share electrons with chlorine atoms

Answer: (b) they can share electrons with chlorine

Explanation: By sharing electrons, non-metals create covalent bonds with other non-metals. Metals, on the other hand, lose electrons while non-metals gain them through the formation of ionic bonds.

Q7: Which of the following are not ionic compounds?

(i) KCl (ii) HCl (iii) CCl₄ (iv) NaCl

(a) (i) and (ii) (b) (ii) and (iii) (c) (iii) and (iv) (d) (i) and (iii)

Answer: (b) (ii) and (iii)

Explanation: Because HCl and CCl₄ are covalent compounds, they are unable to be ionic. Non-ionic compounds contain covalent bonds. Hydrochloric acid (HCl) and carbon tetrachloride (CCl₄) form covalent bonds because two atoms share a pair of electrons.

Since they possess positive and negative ions, sodium chloride (NaCl) and potassium chloride (KCl) form ionic compounds.

Q8: An alloy reacted with dilute hydrochloric acid to produce a gas which ‘pops’ a lighted splint. Theresidue reacted with dilute nitric acid to form a blue solution. Which one of the following pairs of metals ispresent in the alloy?

(a) Copper and lead (b) Lead and magnesium

Answer: (d) Copper and magnesium

Explanation: When zinc combines with hydrochloric acid, hydrogen gas is produced, which causes a lighted splint to pop. When copper residue combines with dilute nitric acid, it forms a blue solution.

Q9: The process in which a carbonate ore is heated strongly in the absence of air to convert it into metaloxide is called

(a) Roasting (b) Calcination (c) Reduction (d) Smelting

Answer: (b) Calcination

Explanation: Calcination is the process of converting a carbonate ore into metal oxide by exposing it to high temperatures in the absence of oxygen. Zinc oxide is produced by heating zinc carbonate in the absence of air.

Q10: Which one among the following is an acidic oxide?

(a) Na₂O (b) CO (c) CO₂(d) Al₂O₃

Answer: (c) CO₂

Explanation: Carbon dioxide is an acidic gas that dissolves with water to produce carbonic acid. Because carbon dioxide does not contain hydrogen, it is not an acid. However, CO₂ dissolves in water to form an acidic solution, just like any other nonmetal oxide.

Q11: Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?

(i) Au (ii) Cu (iii) Na (iv) K

(a) (i) and (ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (iii)and (iv)

Answer: (a) (i) and (ii)

Explanation: Different reduction procedures yield metals that aren’t extremely pure. They contain impurities that must be eliminated before pure metals can be obtained. Electrolytic refining is the most common method for purifying impure metals. Electrolytic refining recovers impurities such as gold, silver, platinum group metals, arsenic, selenium, and tellurium.

Q12: Which one of the following four metals would be displaced from the solution of its salts by the other three metals?

(a) Mg (b) Zn (c) Ag (d) Cu

Answer: (c) Ag

Explanation: Silver is a non-reactive metal that can be easily displaced.

Ag would be displaced from its salt solution by metals such as Mg, Zn, or Cu.
The standard reduction potential for the half-reaction Ag is the maximum among the metals. As a result, the Ag⁺ ion is the most strong oxidising agent among the metals (ions).
Other metals lose an electron while the Ag⁺ ion gains one.

Q13: An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open.It reacts vigorously with water. Identify the element from the following:

(a) Na (b) Mg (c) P (d) Ca

Answer: (a) Na

Explanation: Sodium is a soft alkali metal that can be easily cut with a knife.

Soft metals are malleable metals that can be dented, worked, or cut without shattering.

The softness of sodium metal allows it to be cut with a knife.

Q14: Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of

(a) Galium (b) Aluminium (c) Zinc d) Silver

Answer: (c) Zinc

Explanation: When exposed to air and moisture, iron rusts quickly, and rusting can be prevented by applying a thin layer of zinc to the surface. Galvanisation is the process of applying a zinc coating to iron and steel.

Additional questions

What are alloys ? Name the constituent elements present in bronze and solder metal.

Answer: An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal. Bronze is an alloy of copper and tin, and solder is an alloy of tin and lead.

Alloy: A mixture of two or more metals or a metal and a non-metal, created by melting and mixing the components in a liquid state. Bronze: An alloy made of copper and tin. Solder: An alloy made of tin and lead.

What are ores ? Write the respective methods used to convert sulphide and carbonate ores of metals into their oxides.

Answer: Ores are naturally occurring rocks or sediments containing minerals from which metals can be extracted. Carbonate ores are converted to oxides by calcination, a process of strong heating in the absence of air. Sulphide ores are converted to oxides by roasting, which involves strong heating in the presence of excess air.

Draw the diagram of arrangement of the apparatus used to show the action of steam on metal.

What is malleability ? Name two metals having most malleable property.

Malleability is the property of a metal that allows it to be hammered or rolled into thin sheets. The two most malleable metals are gold and silver. Most malleable metals: are Gold, aluminium and silver. For example, gold is so malleable that it can be beaten into sheets thin enough to be used as gold leaf.

What is sonorous property of metals?

The sonorous property of metals refers to their ability to produce a ringing sound when struck.

When you hit a metal object (like a bell or a steel rod), it vibrates and produces a clear, ringing tone. This happens because metals are good conductors of sound and their structure allows vibrations to pass through efficiently. For example, ells, gongs, and tuning forks are often made from metals like bronze or steel due to this property. If you hit a metal spoon on a table, it gives a ringing sound — that's sonority in action.

Name two metals that are good conductors of heat.

Two metals that are good conductors of heat are Copper and Aluminum. Copper is one of the best conductors of heat and is widely used in cooking utensils and heat exchangers while Aluminum is also a very good heat conductor and is commonly used in cookware and radiators.

When a piece of metal that was stored in kerosene is put into water, then the evolved gas catches fire and burns. i) Which is that metal? ii) Which gas is evolved? iii) Evolved gas catches fire immediately, why?

	Answer
i)	The metal is Sodium (Na)
ii)	The gas released in Hydrogen gas (H₂)
iii)	The evolved gas catches fire because the reaction is exothermic and the heat ignites the flammable hydrogen gas

Ionic compounds in solid state do not conduct electricity, but in molten state are good conductors of electricity. Why ?

In solid state, the ions are fixed in a regular crystal lattice so they cannot move freely. Since free-moving charged particles (ions) are needed to conduct electricity, solid ionic compounds do not conduct electricity. In molten (liquid) state, the heat produced by molten ,materisl breaks the crystal lattice, and the ions become free to move. These freely moving ions can carry electric current.

Write the formation of magnesium chloride (MgCl₂ ) with the help of electron dot structure.

What is the reason for the formation of water when moderately reactive metals react with nitric acid ?

When moderately reactive metals react with nitric acid, water is formed because nitric acid is a powerful oxidizing agent. Unlike other acids, which would typically produce hydrogen gas, nitric acid immediately oxidizes the hydrogen atoms produced in the reaction, turning them into water.

Observe the following chemical equations and answer the question given :

CuO + 2HCl → CuCl₂ + H

CO₂ + Ca(OH)₂ → CaCo₃ + H₂O

Which property of metallic oxide and non-metallic oxide is expressed here ? Explain.

What is the element produced when silicon dioxide reacts with magnesium? Write the equation of the chemical reaction.

Write the chemical equation representing the reaction of zinc with the following:
i) Dilute hydrochloric acid ii) Dilute sulphuric acid

Draw the diagram of an electrolytic cell used in the extraction of copper and label the following parts: (a) Cathode (b) Anode (c) Copper sulphate solution

Name the method of concentration of Haematite ore and explain the method.

Haematite ore is concentrated by the gravity separation method, also known as hydraulic washing. This method works by separating the denser ore particles from the lighter impurities (gangue) based on their difference in specific gravity. The powdered ore is washed with a current of water, which carries the lighter gangue away while the heavier ore settles.

Hydrogen gas is not liberated when a metal like zinc reacts with nitric acid. Why?

Iqbal treated a lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in the reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas. Write chemical equations for both reactions.

Answer: The gas that is liberated is hydrogen gas. To check the presence of hydrogen gas, we can bring a burning matchstick near the evolved gas if the matchstick burns with a pop sound. It confirms the evolution of hydrogen gas.

Reaction with NaOH: M + 2 NaOH → Na₂MO₂ + H2

Reaction with HCl: M + 2 HCl → MCl2 + H2

During the extraction of metals, electrolytic refining is used to obtain pure metals.

(a ) Which material will be used as anode and cathode for refining silver metal in this process?

(b ) Suggest a suitable electrolyte also.

(c ) Where do we get pure silver in this electrolytic cell after passing an electric current?

Answer:

(a ) During electrolytic refining, impure metal is used as anode and pure metal is used as cathode. So. impure silver will be used as an anode, and pure silver will be used as a cathode.

(b ) Silver sulphate or Silver nitrate solution can be an appropriate electrolyte.

(c ) We will obtain pure silver on the cathode because metals are electropositive.

Why should the metal sulphides and carbonates be converted to metal oxides in the extraction process of metal?

Answer:It is easier to obtain metals from their oxides than carbonates or sulphides. So, the ore is first converted into an oxide. A carbonate ore is first converted into oxide ore by calcination. Sulphide ore is converted into oxide ore by roasting.

Generally, when metals are treated with mineral acids, hydrogen gas is liberated, but when metals (except Mn and Mg) are treated with HNO3, hydrogen is not liberated. Why?

Answer:Most metals do not react with HNO3 because nitric acid is a potent oxidising agent. Hence, when metals (except Mn and Mg) are treated with nitric acid, hydrogen gas is not liberated. Only magnesium and manganese can produce hydrogen gas with very dilute nitric acid.

Compound X and aluminium are used to join railway tracks.

(a ) Identify the compound X.

(b ) Name the reaction.

(c ) Write down its reaction.

Answer:

(a ) Compound X Is ferrous oxide (Fe2O3).

(b ) This reaction is called a thermite reaction.

(c ) 2 Al + Fe₂O₃ → 2 Fe + Al₂O3 + heat

When a metal X is treated with cold water, it gives a basic salt Y with the molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved.

Answer:X is Na because the molecular mass of NaOH is 40.

Na (23) + O (16) → NaOH (40)

Hence,X is Sodium.Y is Sodium hydroxide. Z is hydrogen, which catches fire when it reacts with water.

2 Na + 2 H2O → 2 NaOH + H2.

Here oxygen is losing hydrogens, so it is oxidised. The Na has gained oxygen, so it is reduced. Therefore, it is a redox reaction and an H2 displacement reaction. Redox reactions are reactions in which one species is reduced and another is oxidised. Consequently, the oxidation state of the species involved must change.

A non-metal X exists in two different forms, Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.

Answer:

X is carbon. Diamond and graphite are allotropes of carbon. Diamond is the hardest natural substance, and hence Y is diamond. Graphite is a good conductor of electricity, and hence Z is graphite.

The following reaction takes place when the aluminium powder is heated with MnO2

3 MnO2 (s) + 4 Al (s) → 3 Mn (I) + 2 Al2O3 (l) + Heat

(a ) Is aluminium getting reduced?

(b ) Is MnO₂getting oxidised?

Answer:

(a ) No, aluminium is not getting reduced.

(b ) No, MnO₂ is not getting oxidised.

In this reaction, aluminium gets oxidised as oxygen gets combined with it. Since oxygen is removed from MnO₂, it is getting reduced.

What are the constituents of solder alloy? Which property of solder makes it suitable for welding electrical wires?

Answer: Lead and tin are the constituents of the solder alloy. Solder alloy has a low melting point, making it suitable for welding electrical wires.

Metal A, which is used in the thermite process, when heated with oxygen, gives an oxide B, which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B with HI and NaOH.

Answer:Metal A is aluminium, and B is aluminium oxide (Al2O3). The reaction of aluminium oxide with HCl is Al₂O₃ + 6 HCl → 2 AlCl₃ + 3 H₂O

The reaction of aluminium oxide with NaOH:

Al₂O₃ + 2 NaOH → 2 NaAlO₂ + H₂O

A metal that exists as a liquid at room temperature is obtained by heating its sulphide in the presence of air. Identify the metal and its ore and give the reaction involved.

Answer: Mercury is the only metal that exists as a liquid at room temperature. It can be obtained by heating cinnabar (HgS), the sulphide ore of mercury. We can get metals low in activity series by heating or reducing their sulphides or oxides.

The reactions are as follows

2 HgS + 3 O2 → 2 HgO + 2 SO₂

2 HgO → 2 Hg + O2

Give the formulae of the stable binary compounds that would be formed by the combination of the following pairs of elements.

(a ) Mg and N2

(b ) Li and O2

(c ) Al and Cl2

(d ) K and O2

Answer:

(a ) Magnesium nitride (Mg3N2)

(b ) Lithium oxide (Li2O)

(c ) Aluminium chloride (AlCl3)

(d ) Potassium oxide (K2O)

What happens when

(a) ZnCO3 is heated without oxygen?

(b) A mixture of Cu₂O and Cu2S is heated?

Answer:

(a) When zinc carbonate is heated without oxygen, we get zinc oxide and carbon dioxide.

ZnCO3 → ZnO + CO2

(b) When a mixture of copper oxide and copper sulphide is heated. We get the pure copper.

2 Cu2O + Cu2S → 6 Cu + SO2

A non-metal A is an important constituent of our food and forms two oxides, B and C. Oxide B is toxic. In contrast, C causes global warming

(a) Identify A, B, and C

(b) To which Group of Periodic Table does A belong?

Answer:

(a) A is Carbon. B is Carbon monoxide, and C is Carbon-dioxide.

(b) Carbon belongs to Group 14.

Give two examples of the metals that are good conductors and poor conductors of heat, respectively.

Answer:Iron and copper are good conductors of heat and electricity. Lead and mercury are poor conductors of heat and electricity.

Name one metal and one non-metal that exist in the liquid state at room temperature. Also, name two metals having a melting point of less than 310 K (37°C)

Answer:

Mercury (metal) and bromine (non-metal) exist in the liquid state at room temperature. Caesium and gallium are metals with a melting point of less than 310 K.

An element A reacts with water to form a compound B used in whitewashing. The compound B on heating forms an oxide C which gives back B on treatment with water. Identify A, B and C and give the reactions involved.

Answer:

A is calcium. It reacts with water to give calcium hydroxide.

B is calcium hydroxide. It is used for whitewashing.

C is calcium oxide.

The reactions are as follows:

Ca + 2 H2O → Ca(OH)2 + H2

Ca(OH)2 → CaO + H2O

CaO + H2O → Ca(OH)2

An alkali metal A gives a compound B (molecular mass = 40) on reacting with water. The compound B gives a soluble compound C on treatment with aluminium oxide. Identify A, B and C and give the reaction involved.

Answer: Given

x + 16 + 1 = 40

x = 40 – 17 = 23

It is the atomic weight of sodium. Therefore, the alkali metal (A) is sodium, and the reaction is

2 Na + 2 H2O → 2 NaOH + H2.

So, compound B is sodium hydroxide (NaOH). Sodium hydroxide reacts with aluminium oxide (Al2O3) to give sodium aluminate (NaAlO2). Thus, C is sodium aluminate (NaAlO2). The reaction involved is

Al2O3 + 2 NaOH → 2 NaAlO2 + H2O. Hence, A is sodium, B is sodium hydroxide, C is sodium aluminate

Give the reaction involved during extraction of zinc from its ore by

(a ) Roasting of zinc ore

(b ) Calcination of zinc ore

Answer:

(a ) 2 ZnS + 3O2 → 2 ZnO + 2 SO2

(b ) ZnCO3 → ZnO + CO2

A metal M does not liberate hydrogen from acids but reacts with oxygen to give a black colour product. Identify M and black coloured products and explain M’s reaction with oxygen.

Answer: Copper does not react with acids. But copper gives black coloured copper oxide when it reacts with oxygen. Hence, M is copper, and the black coloured product is copper oxide.

2 Cu + O2 → 2 CuO

An element forms an oxide A2O3 which is acidic in nature. Identify A as metal or non-metal.

Answer: Oxides of non-metals are acidic. Hence, A is a non-metal.

We kept a solution of CuSO4 in an iron pot. After a few days, the iron pot was found to have several holes in it. Explain the reason in terms of reactivity. Write the equation of the reaction involved.

Answer: Iron is more reactive than copper. Due to this, iron displaced copper from copper sulphate to form iron sulphate. A portion of the iron pot got dissolved, causing holes in it.

CuSO4 + Fe → FeSO4 + Cu

Long Answer Type Questions

A non-metal A, the largest constituent of air, when heated with H2 in a 1:3 ratio in the presence of a catalyst (Fe), gives a gas B. On heating with Oz, it gives an oxide C. If this oxide is passed into the water in the presence of air, it gives an acid D which acts as a strong oxidising agent.

(a) Identify A, B, C, and D (b) To which group of periodic tables does this non-metal belong?

Answer:

(a) A is nitrogen; because nitrogen is the largest constituent of air. B is ammonia, C is nitrogen dioxide, and D is nitric acid (a potent oxidising agent). When nitrogen is heated with hydrogen in the presence of a catalyst, the following reaction occurs. N2 + 3 H2 → 2 NH3. When nitrogen is heated with oxygen, we get nitrogen dioxide. N2 + 2 O2 → 2 NO2. When nitrogen dioxide is treated with water, we get nitric acid.

NO2 + H2O → HNO3

(b) This non-metal belongs to Group 15.

Give the steps involved in extracting low and medium reactivity metals from their respectivesulphide ores.

Answer: When low and medium reactivity metals are extracted, an individual sulphide ore is first heated in the air. This helps in obtaining the oxide of the metal. It is easier to extract a metal from its oxide than sulphide.

Mercury is a metal of low reactivity. Mercury sulphide (cinnabar) is heated in the air. Mercury sulphide gets oxidised to produce mercury oxide.

2 HgS + 3 O2 → 2 HgO + 2 SO2.

After that, mercury oxide is reduced to obtain mercury.

2 HgO → 2 Hg + O2

Zinc is a metal of medium reactivity. It is found as a zinc blende (ZnS).

Zinc blende is roasted to be converted into zinc oxide. Zinc spar is put under calcination to be converted into zinc oxide.

2 ZnS + 3 O2 → 2 ZnO + 2 SO2

ZnCO3 → ZnO + CO2

Zinc oxide obtained is reduced to zinc metal by heating with carbon (a reducing agent).

ZnO + C → Zn + CO

Explain the following

(a ) Reactivity of Al decreases if it is dipped in HNO3

(b ) Carbon cannot reduce the oxides of Na or Mg

(c ) NaCl is not a conductor of electricity in solid-state, whereas it does conduct electricity in aqueous solution as well as in the molten state

(d ) Iron articles are galvanised.

(e ) Metals like Na, K, Ca and Mg are never found in their free state in nature.

Answer:

(a) When aluminium is dipped in nitric acid, a layer of aluminium oxide is formed on the metal. It happens because nitric acid is a potent oxidising agent. The layer of aluminium oxide prevents further reaction of aluminium.

(b) Sodium and magnesium tend to react with oxygen rather than carbon because sodium and magnesium are highly reactive metals. Hence, carbon cannot reduce the oxides of sodium and magnesium.

(c) Ionic compounds do not conduct electricity in a solid-state but conduct in an aqueous and molten state due to the presence of free electrons. This property is shown by sodium chloride.

(d) Iron articles are galvanised to prevent them from rusting because, after galvanisation, the layer of zinc works as a protective layer.

(e) Metals such as Na, K, Ca and Mg are highly reactive metals, and hence they are not found in their free state.

Given below are the steps for extraction of copper from its ore.

Write the reaction involved.

(a) Roasting of copper (1) sulphide

(b) Reduction of copper (1) oxide with copper (1) sulphide.

(c) Electrolytic refining.

Answer:

(a ) 2 Cu2S + 3 O2 → 2 Cu2O + 2 SO2

(b ) 2 Cu2O + Cu2S → 6 Cu + SO2

(c ) At cathode: Cu2++ 2 e− → Cu

Of the three metals, X, Y and Z. X react with cold water, Y with hot water and Z with steam. Identify X, Y and Z and also arrange them in order of increasing reactivity.

Answer:

X is sodium, Y is magnesium, and Z is iron.

2 Na + 2 H2O → 2 NaOH + H2

Mg + 2 H2O → Mg(OH)2 + H2

3 Fe + 4 H2O → Fe3O4 + 4 H2

Their sequence in reactivity series is: Fe < Mg < Na.

An element A burns with golden flame in the air. It reacts with another element B, atomic number 17, to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also, write down the equations for the reactions involved.

Answer: Element A is sodium metal (Na) as it burns with a golden flame. Element B with atomic number 17 is chlorine (Cl). Sodium and chlorine combine to form sodium chloride, NaCl(compound C). We can write the reaction as 2 Na + Cl2 → 2 NaCl. An aqueous solution of NaCl on electrolysis gives the compound D, sodium hydroxide(NaOH). We can write the reaction as 2 NaCl (aq) + 2 H2O (l) → 2 NaOH (aq) + Cl2 (g) + H2 (g)

Two ores A and B were taken. On heating, ore A gives CO, whereas ore B gives SO2. What steps will you take to convert them into metals?

Answer: A carbonate ore is calcinated to obtain the oxide of the metal. When a carbonate ore is heated, we get carbon dioxide. The following equation shows the calcination of zinc carbonate. ZnCO3 → ZnO + CO2

When a sulphide ore is roasted, we get Sulphur dioxide. Zinc sulphide is roasted to obtain zinc oxide. 2 ZnS + 3 O2 → 2 ZnO + 2 SO2. After any of the above steps, zinc oxide is reduced to obtain pure zinc.

ZnO + C → Zn + CO

Metals and non-metals previous year questions

MCQs(multiple choice)

The amphoteric oxide among the following is
A) Potassium oxide B) Sodium oxide C) Calcium oxide D) Zinc oxide

Answer: D) Zinc oxide (Zinc oxide is amphoteric, meaning it can act both as an acid and a base, whereas the other oxides listed are not amphoteric.)

Brass, German silver and Gunmetal are the alloys of copper. Apart from copper the other commonmetal in them is

(A) zinc (B) tin (C) iron (D) nickel

Answer:A) Zinc (Brass is an alloy of copper and zinc, German silver is copper, zinc, and nickel, and Gunmetal is copper, tin, and zinc. The common metal in brass is zinc.)

You are required to arrange Fe, Zn and Mg in the increasing order of their reactivity. The correct arrangement is

(A) Mg, Zn, Fe (B) Fe, Mg, Zn (C) Fe, Zn, Mg (D) Zn, Mg, Fe.

Answer:A) Mg, Zn, Fe( Magnesium (Mg) is more reactive than zinc (Zn), and zinc is more reactive than iron (Fe).)

The alloy that contains copper and zinc as its constituents, is

(A) Brass (B) bronze C) German silver (D) gunmetal.

Answer:A) Brass(Brass is an alloy made primarily of copper and zinc.)

The reducing agent used in the extraction of silicon is

(A) Magnesium (B) Silica(C) Phosphorus (D) Sulphur.

Answer: A. Magnesium

The electronic configuration of element X is 2, 8, 8, 1 and the electronic configuration of element Y is 2, 8, 7. Then the type of bond formed between these two elements is

(A) covalent (B) hydrogen bond (C) metallic bond (D) ionic bond

Answer:D) Ionic bond (Element X has one electron in its outer shell (likely sodium) and element Y has seven (likely chlorine), so they form an ionic bond by transferring electrons.)

A group that has amphoteric oxides among the following is

(A) Sodium oxide and Copper oxide (B) Aluminium oxide and Zinc oxide

Answer:B) Aluminium oxide and Zinc oxide (Both aluminium oxide (Al₂O₃) and zinc oxide (ZnO) are amphoteric.)

The product produced when calcium oxide reacts with water.

(A) Slaked Lime (B) Gypsum (C) POP (D)Soda

Answer:A) Slaked Lime( Calcium oxide reacts with water to form slaked lime (Ca(OH)₂).)

Sodium metal kept immersed in kerosene oil, because
It is highly reactive and reacts vigorously with air and water.
It is stored to protect it from light.
It is kept to prevent it from rusting.
It is used as a fuel

Answer:A) It is highly reactive and reacts vigorously with air and water.(Sodium metal reacts violently with air and water, so it is kept in kerosene oil to prevent such reactions.)

The metal added to iron to produce stainless steel?
Zinc b) Copper c) Nickel d)Aluminium

Answer:C) Nickel(Nickel is added to iron to make stainless steel, providing resistance to corrosion and enhancing strength)

Which property of metals is used for making bells and strings of musical instruments like Sitar and Violin?

(a) Malleability (b) Sonorousness (c) Ductility (d) Conductivity

Answer:B) Sonorousness( Metals are sonorous, meaning they produce a ringing sound when struck, making them ideal for musical instruments.)

The process in which a carbonate ore is heated strongly in the absence of air to convert it into metal oxide is called

(a) Roasting b) Calcination (c) Reduction (d) Smelting

Answer:B) Calcination(Calcination is the process of heating a carbonate ore in the absence of air to convert it to an oxide.)

Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?

(i) Au (ii) Ca (iii) Na (iv) K

(a) (i) and (ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (iii)and (iv)

Answer:B) (i) and (iii) (Au and Ca). Gold (Au) and calcium (Ca) can be refined by electrolytic refining.

SHORT and LONG Questions

Q1: Aluminium is used for making cooking utensils. Which of the following properties of aluminium areresponsible for the same?

(i) Good thermal conductivity (ii) Good electrical conductivity (iii) Ductility (iv) High melting point

(a) (i) and (ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (i) and (iv)

Answer: (d) (i) and (iv)

Q2: Which property of metals is used for making bells and strings of musical instruments like Sitar andViolin?

(a) Malleability (b) Sonorousness (c) Ductility (d) Conductivity

Answer: (b) Sonorousness

Explanation: Metal’s sonorousness refers to its ability to produce sound. As a result, it’s used to make musical instruments like the Sitar and the Violin’s bells and strings.

Q3: Due to their semiconductor properties the non-metals used in computers, T.V. etc. are

(a) Carbon (b) Bromine (c) Silicon (d) Fluorine

Answer: (c) Silicon

As a result, C is the correct answer.

Q4: Al₂O₃ + 2NaOH →_____ + H₂O

(a) Al(OH)₃ (b) Na₂O (c) NaAlO₂ (d) AlNaO₂

Answer: (c) NaAlO₂

Explanation: Alumina, or dialuminum trioxide, is the chemical formula for Al2O3. It’s a Lewis acid, to be precise.

Sodium hydroxide is abbreviated as NaOH. It’s a solid base. When a base reacts with an acid, the results are usually salt and water.

As a result, lewis acid alumina combines with the base sodium hydroxide to generate salt and water in this reaction.

Q5: Which of the following pairs will give displacement reactions?

(a) FeSO₄ solution and Copper metal

(b) AgNO₃ solution and Copper metal

(d) NaCl solution and Copper metal

Answer: (b) AgNO₃ solution and Copper metal

Explanation: The displacement reaction occurs when copper metal and silver nitrate solution are combined, and the chemical equation is: Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag.

Q6: Non-metals form covalent chlorides because

(a) they can give electrons to chlorine

(b) they can share electrons with chlorine

(d) they cannot share electrons with chlorine atoms

Answer: (b) they can share electrons with chlorine

Explanation: By sharing electrons, non-metals create covalent bonds with other non-metals. Metals, on the other hand, lose electrons while non-metals gain them through the formation of ionic bonds.

Q7: Which of the following are not ionic compounds?

(i) KCl (ii) HCl (iii) CCl₄ (iv) NaCl

(a) (i) and (ii) (b) (ii) and (iii) (c) (iii) and (iv) (d) (i) and (iii)

Answer: (b) (ii) and (iii)

Since they possess positive and negative ions, sodium chloride (NaCl) and potassium chloride (KCl) form ionic compounds.

Q8: An alloy reacted with dilute hydrochloric acid to produce a gas which ‘pops’ a lighted splint. Theresidue reacted with dilute nitric acid to form a blue solution. Which one of the following pairs of metals ispresent in the alloy?

(a) Copper and lead (b) Lead and magnesium

Answer: (d) Copper and magnesium

Explanation: When zinc combines with hydrochloric acid, hydrogen gas is produced, which causes a lighted splint to pop. When copper residue combines with dilute nitric acid, it forms a blue solution.

Q9: The process in which a carbonate ore is heated strongly in the absence of air to convert it into metaloxide is called

(a) Roasting (b) Calcination (c) Reduction (d) Smelting

Answer: (b) Calcination

Q10: Which one among the following is an acidic oxide?

(a) Na₂O (b) CO (c) CO₂(d) Al₂O₃

Answer: (c) CO₂

Q11: Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?

(i) Au (ii) Cu (iii) Na (iv) K

(a) (i) and (ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (iii)and (iv)

Answer: (a) (i) and (ii)

Q12: Which one of the following four metals would be displaced from the solution of its salts by the other three metals?

(a) Mg (b) Zn (c) Ag (d) Cu

Answer: (c) Ag

Explanation: Silver is a non-reactive metal that can be easily displaced.

Ag would be displaced from its salt solution by metals such as Mg, Zn, or Cu.
The standard reduction potential for the half-reaction Ag is the maximum among the metals. As a result, the Ag⁺ ion is the most strong oxidising agent among the metals (ions).
Other metals lose an electron while the Ag⁺ ion gains one.

Q13: An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open.It reacts vigorously with water. Identify the element from the following:

(a) Na (b) Mg (c) P (d) Ca

Answer: (a) Na

Explanation: Sodium is a soft alkali metal that can be easily cut with a knife.

Soft metals are malleable metals that can be dented, worked, or cut without shattering.

The softness of sodium metal allows it to be cut with a knife.

Q14: Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of

(a) Galium (b) Aluminium (c) Zinc d) Silver

Answer: (c) Zinc

Additional questions

What are alloys ? Name the constituent elements present in bronze and solder metal.

Answer: An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal. Bronze is an alloy of copper and tin, and solder is an alloy of tin and lead.

What are ores ? Write the respective methods used to convert sulphide and carbonate ores of metals into their oxides.

Draw the diagram of arrangement of the apparatus used to show the action of steam on metal.

What is malleability ? Name two metals having most malleable property.

What is sonorous property of metals?

The sonorous property of metals refers to their ability to produce a ringing sound when struck.

Name two metals that are good conductors of heat.

Two metals that are good conductors of heat are Copper and Aluminum. Copper is one of the best conductors of heat and is widely used in cooking utensils and heat exchangers whileAluminum is also a very good heat conductor and is commonly used in cookware and radiators.

When a piece of metal that was stored in kerosene is put into water, then the evolved gas catches fire and burns.
i) Which is that metal? ii) Which gas is evolved? iii) Evolved gas catches fire immediately, why?

Part	Answer
i)	The metal is Sodium (Na)
ii)	The gas released in Hydrogen gas (H₂)
iii)	The evolved gas catches fire because the reaction is exothermic and the heat ignites the flammable hydrogen gas

Ionic compounds in solid state do not conduct electricity, but in molten state are good conductors of electricity. Why ?

Write the formation of magnesium chloride (MgCl₂ ) with the help of electron dot structure.

What is the reason for the formation of water when moderately reactive metals react with nitric acid ?

Observe the following chemical equations and answer the question given :

CuO + 2HCl → CuCl₂ + H

CO₂ + Ca(OH)₂ → CaCo₃ + H₂O

Which property of metallic oxide and non-metallic oxide is expressed here ? Explain.

What is the element produced when silicon dioxide reacts with magnesium? Write the equation of the chemical reaction.

Write the chemical equation representing the reaction of zinc with the following:
i) Dilute hydrochloric acid ii) Dilute sulphuric acid

Draw the diagram of an electrolytic cell used in the extraction of copper and label the following parts: (a) Cathode (b) Anode (c) Copper sulphate solution

Name the method of concentration of Haematite ore and explain the method.

Hydrogen gas is not liberated when a metal like zinc reacts with nitric acid. Why?

Iqbal treated a lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in the reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas. Write chemical equations for both reactions.

Reaction with NaOH:M + 2 NaOH → Na₂MO₂ + H2

Reaction with HCl:M + 2 HCl → MCl2 + H2

During the extraction of metals, electrolytic refining is used to obtain pure metals.

(a ) Which material will be used as anode and cathode for refining silver metal in this process?

(b ) Suggest a suitable electrolyte also.

(c ) Where do we get pure silver in this electrolytic cell after passing an electric current?

Answer:

(a ) During electrolytic refining, impure metal is used as anode and pure metal is used as cathode. So. impure silver will be used as an anode, and pure silver will be used as a cathode.

(b ) Silver sulphate or Silver nitrate solution can be an appropriate electrolyte.

(c ) We will obtain pure silver on the cathode because metals are electropositive.

Why should the metal sulphides and carbonates be converted to metal oxides in the extraction process of metal?

Generally, when metals are treated with mineral acids, hydrogen gas is liberated, but when metals (except Mn and Mg) are treated with HNO3, hydrogen is not liberated. Why?

Compound X and aluminium are used to join railway tracks.

(a ) Identify the compound X.

(b ) Name the reaction.

(c ) Write down its reaction.

Answer:

(a ) Compound X Is ferrous oxide (Fe2O3).

(b ) This reaction is called a thermite reaction.

(c ) 2 Al + Fe₂O₃ → 2 Fe + Al₂O3 + heat

When a metal X is treated with cold water, it gives a basic salt Y with the molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved.

Answer:X is Na because the molecular mass of NaOH is 40.

Na (23) + O (16) → NaOH (40)

Hence,X is Sodium.Y is Sodium hydroxide.Z is hydrogen, which catches fire when it reacts with water.

2 Na + 2 H2O → 2 NaOH + H2.

A non-metal X exists in two different forms, Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.

Answer:

X is carbon. Diamond and graphite are allotropes of carbon. Diamond is the hardest natural substance, and hence Y is diamond. Graphite is a good conductor of electricity, and hence Z is graphite.

The following reaction takes place when the aluminium powder is heated with MnO2

3 MnO2 (s) + 4 Al (s) → 3 Mn (I) + 2 Al2O3 (l) + Heat

(a ) Is aluminium getting reduced?

(b ) Is MnO₂getting oxidised?

Answer:

(a ) No, aluminium is not getting reduced.

(b ) No, MnO₂ is not getting oxidised.

In this reaction, aluminium gets oxidised as oxygen gets combined with it. Since oxygen is removed from MnO₂, it is getting reduced.

What are the constituents of solder alloy? Which property of solder makes it suitable for welding electrical wires?

Answer:Lead and tin are the constituents of the solder alloy. Solder alloy has a low melting point, making it suitable for welding electrical wires.

Metal A, which is used in the thermite process, when heated with oxygen, gives an oxide B, which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B with HI and NaOH.

Answer:Metal A is aluminium, and B is aluminium oxide (Al2O3).The reaction of aluminium oxide with HCl is Al₂O₃ + 6 HCl → 2 AlCl₃ + 3 H₂O

The reaction of aluminium oxide with NaOH:

Al₂O₃ + 2 NaOH → 2 NaAlO₂ + H₂O

A metal that exists as a liquid at room temperature is obtained by heating its sulphide in the presence of air. Identify the metal and its ore and give the reaction involved.

Answer:Mercury is the only metal that exists as a liquid at room temperature. It can be obtained by heating cinnabar (HgS), the sulphide ore of mercury. We can get metals low in activity series by heating or reducing their sulphides or oxides.

The reactions are as follows

2 HgS + 3 O2 → 2 HgO + 2 SO₂

2 HgO → 2 Hg + O2

Give the formulae of the stable binary compounds that would be formed by the combination of the following pairs of elements.

(a ) Mg and N2

(b ) Li and O2

(c ) Al and Cl2

(d ) K and O2

Answer:

(a ) Magnesium nitride (Mg3N2)

(b ) Lithium oxide (Li2O)

(c ) Aluminium chloride (AlCl3)

(d ) Potassium oxide (K2O)

What happens when

(a) ZnCO3 is heated without oxygen?

(b) A mixture of Cu₂O and Cu2S is heated?

Answer:

(a) When zinc carbonate is heated without oxygen, we get zinc oxide and carbon dioxide.

ZnCO3 → ZnO + CO2

(b) When a mixture of copper oxide and copper sulphide is heated. We get the pure copper.

2 Cu2O + Cu2S → 6 Cu + SO2

A non-metal A is an important constituent of our food and forms two oxides, B and C. Oxide B is toxic. In contrast, C causes global warming

(a) Identify A, B, and C

(b) To which Group of Periodic Table does A belong?

Answer:

(a) A is Carbon. B is Carbon monoxide, and C is Carbon-dioxide.

(b) Carbon belongs to Group 14.

Give two examples of the metals that are good conductors and poor conductors of heat, respectively.

Answer:Iron and copper are good conductors of heat and electricity.Lead and mercury are poor conductors of heat and electricity.

Name one metal and one non-metal that exist in the liquid state at room temperature. Also, name two metals having a melting point of less than 310 K (37°C)

Answer:

Mercury (metal) and bromine (non-metal) exist in the liquid state at room temperature. Caesium and gallium are metals with a melting point of less than 310 K.

An element A reacts with water to form a compound B used in whitewashing. The compound B on heating forms an oxide C which gives back B on treatment with water. Identify A, B and C and give the reactions involved.

Answer:

A is calcium. It reacts with water to give calcium hydroxide.

B is calcium hydroxide. It is used for whitewashing.

C is calcium oxide.

The reactions are as follows:

Ca + 2 H2O → Ca(OH)2 + H2

Ca(OH)2 → CaO + H2O

CaO + H2O → Ca(OH)2

An alkali metal A gives a compound B (molecular mass = 40) on reacting with water. The compound B gives a soluble compound C on treatment with aluminium oxide. Identify A, B and C and give the reaction involved.

Answer:Given

x + 16 + 1 = 40

x = 40 – 17 = 23

It is the atomic weight of sodium.Therefore, the alkali metal (A) is sodium, and the reaction is

2 Na + 2 H2O → 2 NaOH + H2.

So, compound B is sodium hydroxide (NaOH).Sodium hydroxide reacts with aluminium oxide (Al2O3) to give sodium aluminate (NaAlO2). Thus, C is sodium aluminate (NaAlO2). The reaction involved is

Al2O3 + 2 NaOH → 2 NaAlO2 + H2O.Hence, A is sodium, B is sodium hydroxide, C is sodium aluminate

Give the reaction involved during extraction of zinc from its ore by

(a ) Roasting of zinc ore

(b ) Calcination of zinc ore

Answer:

(a ) 2 ZnS + 3O2 → 2 ZnO + 2 SO2

(b ) ZnCO3 → ZnO + CO2

A metal M does not liberate hydrogen from acids but reacts with oxygen to give a black colour product. Identify M and black coloured products and explain M’s reaction with oxygen.

Answer:Copper does not react with acids. But copper gives black coloured copper oxide when it reacts with oxygen. Hence, M is copper, and the black coloured product is copper oxide.

2 Cu + O2 → 2 CuO

An element forms an oxide A2O3 which is acidic in nature. Identify A as metal or non-metal.

Answer:Oxides of non-metals are acidic. Hence, A is a non-metal.

We kept a solution of CuSO4 in an iron pot. After a few days, the iron pot was found to have several holes in it. Explain the reason in terms of reactivity. Write the equation of the reaction involved.

Answer:Iron is more reactive than copper. Due to this, iron displaced copper from copper sulphate to form iron sulphate. A portion of the iron pot got dissolved, causing holes in it.

CuSO4 + Fe → FeSO4 + Cu

Long Answer Type Questions

A non-metal A, the largest constituent of air, when heated with H2 in a 1:3 ratio in the presence of a catalyst (Fe), gives a gas B. On heating with Oz, it gives an oxide C. If this oxide is passed into the water in the presence of air, it gives an acid D which acts as a strong oxidising agent.

(a) Identify A, B, C, and D(b) To which group of periodic tables does this non-metal belong?

Answer:

(a) A is nitrogen; because nitrogen is the largest constituent of air. B is ammonia, C is nitrogen dioxide, and D is nitric acid (a potent oxidising agent).When nitrogen is heated with hydrogen in the presence of a catalyst, the following reaction occurs.N2 + 3 H2 → 2 NH3.When nitrogen is heated with oxygen, we get nitrogen dioxide.N2 + 2 O2 → 2 NO2. When nitrogen dioxide is treated with water, we get nitric acid.

NO2 + H2O → HNO3

(b) This non-metal belongs to Group 15.

Give the steps involved in extracting low and medium reactivity metals from their respectivesulphide ores.

Answer:When low and medium reactivity metals are extracted, an individual sulphide ore is first heated in the air. This helps in obtaining the oxide of the metal. It is easier to extract a metal from its oxide than sulphide.

Mercury is a metal of low reactivity. Mercury sulphide (cinnabar) is heated in the air. Mercury sulphide gets oxidised to produce mercury oxide.

2 HgS + 3 O2 → 2 HgO + 2 SO2.

After that, mercury oxide is reduced to obtain mercury.

2 HgO → 2 Hg + O2

Zinc is a metal of medium reactivity. It is found as a zinc blende (ZnS).

Zinc blende is roasted to be converted into zinc oxide. Zinc spar is put under calcination to be converted into zinc oxide.

2 ZnS + 3 O2 → 2 ZnO + 2 SO2

ZnCO3 → ZnO + CO2

Zinc oxide obtained is reduced to zinc metal by heating with carbon (a reducing agent).

ZnO + C → Zn + CO

Explain the following

(a ) Reactivity of Al decreases if it is dipped in HNO3

(b ) Carbon cannot reduce the oxides of Na or Mg

(c )NaCl is not a conductor of electricity in solid-state, whereas it does conduct electricity in aqueous solution as well as in the molten state

(d ) Iron articles are galvanised.

(e ) Metals like Na, K, Ca and Mg are never found in their free state in nature.

Answer:

(b) Sodium and magnesium tend to react with oxygen rather than carbon because sodium and magnesium are highly reactive metals. Hence, carbon cannot reduce the oxides of sodium and magnesium.

(c) Ionic compounds do not conduct electricity in a solid-state but conduct in an aqueous and molten state due to the presence of free electrons. This property is shown by sodium chloride.

(d) Iron articles are galvanised to prevent them from rusting because, after galvanisation, the layer of zinc works as a protective layer.

(e) Metals such as Na, K, Ca and Mg are highly reactive metals, and hence they are not found in their free state.

Given below are the steps for extraction of copper from its ore.

Write the reaction involved.

(a) Roasting of copper (1) sulphide

(b) Reduction of copper (1) oxide with copper (1) sulphide.

(c) Electrolytic refining.

Answer:

(a ) 2 Cu2S + 3 O2 → 2 Cu2O + 2 SO2

(b ) 2 Cu2O + Cu2S → 6 Cu + SO2

(c ) At cathode: Cu2++ 2 e− → Cu

Of the three metals, X, Y and Z. X react with cold water, Y with hot water and Z with steam. Identify X, Y and Z and also arrange them in order of increasing reactivity.

Answer:

X is sodium, Y is magnesium, and Z is iron.

2 Na + 2 H2O → 2 NaOH + H2

Mg + 2 H2O → Mg(OH)2 + H2

3 Fe + 4 H2O → Fe3O4 + 4 H2

Their sequence in reactivity series is: Fe < Mg < Na.

An element A burns with golden flame in the air. It reacts with another element B, atomic number 17, to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also, write down the equations for the reactions involved.

Answer:Element A is sodium metal (Na) as it burns with a golden flame.Element B with atomic number 17 is chlorine (Cl).Sodium and chlorine combine to form sodium chloride, NaCl(compound C).We can write the reaction as2 Na + Cl2 → 2 NaCl.An aqueous solution of NaCl on electrolysis gives the compound D, sodium hydroxide(NaOH). We can write the reaction as2 NaCl (aq) + 2 H2O (l) → 2 NaOH (aq) + Cl2 (g) + H2 (g)

Two ores A and B were taken. On heating, ore A gives CO, whereas ore B gives SO2. What steps will you take to convert them into metals?

Answer:A carbonate ore is calcinated to obtain the oxide of the metal. When a carbonate ore is heated, we get carbon dioxide. The following equation shows the calcination of zinc carbonate.ZnCO3 → ZnO + CO2

When a sulphide ore is roasted, we get Sulphur dioxide. Zinc sulphide is roasted to obtain zinc oxide.2 ZnS + 3 O2 → 2 ZnO + 2 SO2.After any of the above steps, zinc oxide is reduced to obtain pure zinc.

ZnO + C → Zn + CO

LBA Solutions

Weightage – Difficulty Level

Difficulty Level	Weightage	No. of Questions	Marks
Easy	30%	26	39
Average	50%	29	65
Difficult	20%	13	26

Learning Points

Physical properties of metals and non-metals
Chemical properties of metals
What happens when metals are burned in air
What happens when metals react with water
What happens when metals react with acids
Reaction of metals with solutions of other metallic salts
Reactivity series
How metals and non-metals react
Alloys and their uses
Availability of metals, metallization, and enrichment of ores
Corrosion and its prevention

MCQs

Which of the following pairs causes a displacement reaction?

A. NaCl solution and copper metal
B. MgCl₂ solution and aluminium metal
C. FeSO₄ solution and silver metal
D. AgNO₃ solution and copper metal

Which of the following methods is suitable for preventing rusting of iron tawa pan?

A. Applying grease
B. Painting
C. Coating with zinc
D. All of the above

Food cans are coated with tin and not with copper. Reasons are:

A. Zinc is more expensive than tin
B. The melting point of zinc is higher than that of tin
C. Zinc is more reactive than tin
D. Zinc is less reactive than tin

The gas released when metals react with acids. (MODEL PAPER)

A. H₂
B. CO₂
C. SO₂
D. NO₂

A green layer is formed when copper reacts with moist carbon dioxide in the air. (SUP. EXAM)

A. Copper carbonate
B. Copper chloride
C. Copper nitrate
D. Copper oxide

Which of the following pairs causes a displacement reaction?

A. NaCl + Cu
B. MgCl₂ + Al
C. FeSO₄ + Ag
D. AgNO₃ + Cu

Observe the following equation and identify the correct statement:
2AgNO₃ + Cu → Cu(NO₃)₂ + 2Ag

A. Copper is more reactive than iron and silver
B. Iron is less reactive than copper and silver
C. Copper is more reactive than silver but less reactive than iron
D. Silver is more reactive than copper and iron

The electron configuration of element X is 2,8,8,1 and Y is 2,8,7. What is the type of bond formed between these elements? (MARCH 2019)

A. Covalent bond
B. Metallic bond
C. Hydrogen bond
D. Ionic bond

The correct order to write these metals in increasing order of reactivity is:
Al, Na, K, Ca, Mg

A. Al < Mg < Ca < Na < K
B. K < Mg < Ca < Na < Al
C. K < Na < Ca < Mg < Al
D. Al < Na < Mg < Ca < K

A process used to convert metal sulphide ores into their oxides.

A. Calcination
B. Roasting
C. Reduction
D. Electrolysis

Which metal displaces copper from copper sulphate solution? (JUNE 2022)

A. Mercury
B. Gold
C. Iron
D. Silver

Observe the following chemical reactions:
Fe + CuSO₄ → FeSO₄ + Cu
Zn + FeSO₄ → ZnSO₄ + Fe

The order of decreasing reactivity of the metals is:

A. Zn > Fe > Cu
B. Fe > Cu > Zn
C. Zn > Cu > Fe
D. Cu > Fe > Zn

Observe the equations of the following chemical reactions: (SEP 2021)
Zn + FeSO₄ → ZnSO₄ + Fe
2Al + 3ZnSO₄ → Al₂(SO₄)₃ + 3Zn

The order of increasing reactivity of the metals is:

A. Fe < Zn < Al
B. Al < Zn < Fe
C. Zn < Fe < Al
D. Al < Fe < Zn

Aluminium, iron, magnesium and zinc reacted with concentrated hydrochloric acid. Write the reactivity of these metals in decreasing order. (JUNE 2024)

A. Mg > Al > Zn > Fe
B. Al > Mg > Fe > Zn
C. Fe > Zn > Al > Mg
D. Fe > Mg > Zn > Al

Which of the following chemical reactions is possible? (APR 2019)

A. FeSO₄ + Pb → PbSO₄ + Fe
B. ZnSO₄ + Fe → FeSO₄ + Zn
C. 2AgNO₃ + Cu → Cu(NO₃)₂ + 2Ag
D. PbCl₂ + Cu → CuCl₂ + Pb

The electron configurations of elements A, B and C are:
C = 2,8,7 B = 2,8 A = 2,8,2

Among these, the elements which react with each other to form an ionic compound are (MQP 2025)

A. Elements A and B
B. Elements B and C
C. Elements A and C
D. Elements A and C

Answer Key – MCQs

Answer: D. AgNO₃ solution and copper metal
Answer: D. All of the above
Answer: C. Zinc is more reactive than tin
Answer: A. H₂
Answer: A. Copper carbonate
Answer: D. AgNO₃ + Cu
Answer: C. Copper is more reactive than silver but less reactive than iron
Answer: D. Ionic bond
Answer: A. Al < Mg < Ca < Na < K
Answer: B. Roasting
Answer: C. Iron
Answer: A. Zn > Fe > Cu
Answer: A. Fe < Zn < Al
Answer: A. Mg > Al > Zn > Fe
Answer: C. 2AgNO₃ + Cu → Cu(NO₃)₂ + 2Ag
Answer: C. Elements A and C

One Mark Questions

What are amphoteric oxides? -
Name two metals that react with highly concentrated nitric acid. -
Name the good conductors of heat and the poor conductors of heat. -
Name the non-metal that conducts electricity. -
What is ductility? -
What are ionic compounds? -
An iron ring needs to be plated with copper. How can this be done without using electricity? (April 2020) -
What is thermite reaction? -
Which metals do not corrode easily? -
. What is an alloy? -
Name the metals that are found in the free state. -
What is the chemical method used to obtain a metal from its oxide? -
Ionic compounds have the highest melting points. Why? -

One Mark Answer Ke

What are amphoteric oxides?
Amphoteric oxides are oxides that react with both acids and bases to produce salt and water.

Name two metals that react with highly concentrated nitric acid.
Copper and Silver.

Name the good conductors of heat and the poor conductors of heat.
Metals are good conductors of heat. Non-metals are poor conductors of heat.

Name the non-metal that conducts electricity.
Graphite.

What is ductility?
Ductility is the property of a metal by which it can be drawn into thin wires.

What are ionic compounds?
Ionic compounds are compounds formed by the transfer of electrons from one atom to another, resulting in the formation of oppositely charged ions.

An iron ring needs to be plated with copper. How can this be done without using electricity? (April 2020)
It can be done by dipping the iron ring in copper sulphate solution. Copper gets deposited on iron by displacement reaction.

What is thermite reaction?
The thermite reaction is a highly exothermic reaction between aluminium powder and iron oxide to produce molten iron.

Which metals do not corrode easily?
Gold and Platinum.

What is an alloy?
An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal.

Name the metals that are found in the free state.
Gold, Platinum and Silver.

What is the chemical method used to obtain a metal from its oxide?
Reduction.

Ionic compounds have the highest melting points. Why?
Because ionic compounds have strong electrostatic forces of attraction between oppositely charged ions.

2 Marks/3 Marks Questions

Which gas is released when concentrated hydrochloric acid is added to a reactive metal?
Write the balanced chemical equation for the reaction of iron with concentrated H₂SO₄.
Write the balanced chemical equations for the reaction of aluminium oxide with:
a) Acid
b) Base
Mention any four properties of ionic compounds. (June 2022)
Why does calcium metal not ignite and burn even though it releases hydrogen gas when it reacts with water? Write its chemical equation. (April 2022)
Name two metals that react quickly with cold water.
Write the products formed when these metals react with cold water.
Which physical properties of metals are used in the following situations? (April 2020)
i) Gold is used in making jewellery.
ii) Nickel is used in guitar strings.
List any four physical properties of metals. (March 2025)
State any four physical properties of non-metals.
Name the metals that match the following physical properties:
i) It is liquid at room temperature
ii) It can be easily cut with a knife
iii) It is a good conductor of heat
iv) It is a poor conductor of heat
Write chemical equations for the following reactions. (SUP. EXAM / MQP 2025)
a) Reaction of iron with steam
b) Reaction of calcium with water
Carbon cannot reduce oxides of metals like sodium, magnesium and aluminium. Why?
Then how are these metals separated from their ores?
Name two metals that displace hydrogen from concentrated acids and name two metals that do not displace hydrogen.
In the electrolytic purification of metal ‘M’, which substance is taken as:
a) Anode
b) Cathode
c) Electrolytic solution
Write the steps taken to prevent iron from rusting. (Mar/Apr 2025)
250 ml of water is taken in beaker A and beaker B. 5 g of sodium metal is added to beaker A and 5 g of calcium metal is added to beaker B. What is the reason for the observations made here? (2024 – Exam 3)
i) When a metal reacts with concentrated nitric acid, hydrogen gas is not released. Give a reason.
ii) Write a balanced chemical equation for the reaction of aluminium with concentrated hydrochloric acid.
What is galvanization? How does it help in preventing iron from rusting?
A metal reduces iron oxide. This reaction is used in the repair of broken railway tracks.
a) Name the metal used.
b) Name the reaction.
c) Write the balanced chemical equation.
What are alloys? Name the constituent elements in:
a) Bronze
b) Solder
What are ores? Write the methods of converting the following ores into their respective oxides in the correct order:
a) Sulphide ores
b) Carbonate ores
State the difference between smelting and roasting.
State the method used for reducing cinnabar.
Pieces of zinc, iron, magnesium and copper are taken in test tubes A, B, C and D respectively. The same amount of ferrous sulphate solution is added to each test tube.
a) In which test tubes does the chemical reaction take place?
b) Why does the reaction occur only in those test tubes?
c) Write the balanced chemical equations.
Observe the test tubes A, B and C shown in the given diagram. (Exam-2, May 2025)
a) In which test tube does the iron nail rust? Why?
b) Why do the iron nails in the other two test tubes not rust?
Give scientific reasons for the following: (April 2019)
i) Ionic compounds are electrical insulators in the solid state but good conductors of electricity in the molten state.
ii) Sodium and potassium metals are stored in kerosene.
iii) Although aluminium is a reactive metal, it is used in the manufacture of cooking utensils.
A student took sulphur powder in a laboratory spoon and heated it. He inverted the test tube and collected the gas released.
A) How do the collected gases behave with:
i) Dry litmus paper
ii) Wet litmus paper
B) Write the balanced chemical equation for the reaction taking place.
Draw a diagram showing the behaviour of steam on a metal and identify the following parts: (June 2019)
a) Outlet
b) Hydrogen gas
Draw a diagram showing the electrolysis of copper and identify the following parts:
a) Cathode
b) Mud
How are metals in the middle of the reactivity series treated to obtain their metals? Explain. (April 2023)
a) How do silver and copper objects lose their surface lustre? (2024 Exam-1)
b) How does galvanization protect iron objects?
c) Why is aluminium oxide called an amphoteric oxide? (MQP)

2 Marks / 3 Marks Answer Key

Hydrogen gas (H₂) is released when concentrated hydrochloric acid reacts with a reactive metal.
Fe + 2H₂SO₄ (conc) → FeSO₄ + SO₂ + 2H₂O
a) Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
b) Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O
Properties of ionic compounds:
- High melting and boiling points
- Hard and brittle
- Soluble in water
- Conduct electricity in molten or aqueous state
Calcium does not ignite because the heat produced is not sufficient to burn hydrogen.
Ca + 2H₂O → Ca(OH)₂ + H₂
Metals: Sodium and Potassium.
They form hydroxides and hydrogen gas when reacting with cold water.
i) Gold – Lustre and malleability
ii) Nickel – Ductility and tensile strength
Four physical properties of metals:
- Lustrous
- Malleable
- Ductile
- Good conductors of heat and electricity
Four physical properties of non-metals:
- Dull
- Brittle
- Poor conductors
- Non-sonorous
i) Mercury
ii) Sodium
iii) Copper
iv) Lead
a) 3Fe + 4H₂O (steam) → Fe₃O₄ + 4H₂
b) Ca + 2H₂O → Ca(OH)₂ + H₂
Carbon cannot reduce them because they are more reactive than carbon.
They are extracted by electrolysis.
Displace hydrogen: Zinc, Iron
Do not displace hydrogen: Copper, Silver
a) Impure metal – Anode
b) Pure metal – Cathode
c) Aqueous solution of metal salt
Methods to prevent rusting:
- Painting
- Oiling/greasing
- Galvanization
- Alloying
Sodium reacts vigorously with water, producing more heat.
Calcium reacts less vigorously.
i) Nitric acid is a strong oxidising agent; it oxidises hydrogen to water.
ii) 2Al + 6HCl → 2AlCl₃ + 3H₂
Galvanization is coating iron with zinc to prevent rusting.
a) Aluminium
b) Thermite reaction
c) Fe₂O₃ + 2Al → Al₂O₃ + 2Fe
Alloys are homogeneous mixtures of metals.
a) Bronze – Copper + Tin
b) Solder – Lead + Tin
Ores are minerals from which metals are extracted.
Sulphide ores – Roasting
Carbonate ores – Calcination
Smelting – Extraction of metal from oxide by heating with reducing agent.
Roasting – Heating sulphide ore in air.
Cinnabar is reduced by roasting followed by heating.
a) Reaction occurs in magnesium and zinc.
b) They are more reactive than iron.
c) Zn + FeSO₄ → ZnSO₄ + Fe
Rusting occurs in test tube containing air and water.
Other test tubes lack oxygen or water.
i) Ions are free in molten state but fixed in solid state.
ii) To prevent reaction with air and moisture.
iii) It forms a protective oxide layer.
Dry litmus – No change
Wet litmus – Turns red
S + O₂ → SO₂
Steam reacts with heated metal producing hydrogen gas.
Cathode – Pure copper
Mud – Anode sludge
Metals in middle reactivity series are extracted by reduction with carbon.
a) They react with oxygen, sulphur and carbon dioxide forming compounds.
b) Zinc coating prevents contact with air and moisture.
c) It reacts with both acids and bases.

4 Mark Questions

A) Show the formation of Na₂O and MgO by the transfer of electrons. (April 2023 / June 2019)
B) What are the ions present in the following compounds?
i) Sodium oxide (Na₂O)
ii) Magnesium oxide (MgO)
Pieces of four metals A, B, C and D are taken and placed one after the other in the following solutions. The results are shown below:

Metals	Iron(II) sulphate	Copper(II) sulphate	Zinc sulphate	Silver nitrate
A	No reaction	Displacement	—	—
B	Displacement	—	No reaction	—
C	No reaction	No reaction	No reaction	Displacement
D	No reaction	No reaction	No reaction	No reaction

Answer the following:
a) Which is the most reactive metal?
b) What will you observe if metal B is placed in copper(II) sulphate solution?
c) Write the metals A, B, C and D in decreasing order of reactivity.

Also,
a) Draw the electron dot structures of sodium, oxygen and magnesium.
b) Explain the following terms:
i) Minerals
ii) Iron
iii) Mud

In which cases can displacement reactions be observed when oxides of zinc, magnesium and copper are treated with the following metals?

Metal Oxide	Zinc (Zn)	Magnesium (Mg)	Copper (Cu)
Zinc Oxide (ZnO)	No reaction	Displacement	No reaction
Magnesium Oxide (MgO)	No reaction	No reaction	No reaction
Copper Oxide (CuO)	Displacement	Displacement	No reaction

Give reasons for the following: (April 2019)
a) Iron alloys are more useful than pure iron.
b) Copper gradually loses its brown lustre when exposed to air.
c) Aluminium oxide is called an amphoteric oxide.
d) Hydrogen gas is not released when a metal reacts with concentrated nitric acid.
Express the formation of magnesium chloride with the help of an electron dot structure. (MQP 2025)

4 Mark Answer Key

A) Formation of Na₂O and MgO by transfer of electrons:

Formation of Sodium Oxide (Na₂O):
Na → Na⁺ + e⁻
O + 2e⁻ → O²⁻

Two sodium atoms each lose one electron and oxygen gains two electrons.
2Na + O → Na₂O

Formation of Magnesium Oxide (MgO):
Mg → Mg²⁺ + 2e⁻
O + 2e⁻ → O²⁻

Magnesium loses two electrons and oxygen gains two electrons.
Mg + O → MgO

B) Ions present:
i) Sodium oxide (Na₂O): Na⁺ and O²⁻
ii) Magnesium oxide (MgO): Mg²⁺ and O²⁻

a) Most reactive metal: B (because it displaces iron and is more reactive).

b) Observation when metal B is placed in copper(II) sulphate solution:
A displacement reaction will occur. The blue colour of copper sulphate solution fades and reddish-brown copper is deposited.

c) Decreasing order of reactivity:
B > A > C > D

Also,

a) Electron dot structures:
Sodium (Na): Na • (1 valence electron)
Oxygen (O): O with 6 valence electrons (•• •• ••)
Magnesium (Mg): Mg •• (2 valence electrons)

b) Explanation of terms:
i) Minerals: Naturally occurring substances in the earth’s crust containing metals or their compounds.

ii) Iron: A strong, hard magnetic metal used for making tools, machines and construction materials.

iii) Mud: A mixture of soil and water forming a soft, sticky substance.

Displacement reactions observed:

• Magnesium displaces zinc from zinc oxide.
Mg + ZnO → MgO + Zn

• Zinc displaces copper from copper oxide.
Zn + CuO → ZnO + Cu

• Magnesium displaces copper from copper oxide.
Mg + CuO → MgO + Cu

No other combinations show displacement reactions.

Give reasons:

a) Iron alloys are more useful than pure iron because they are stronger, harder and more resistant to corrosion.

b) Copper loses its brown layer because it reacts with air, moisture and carbon dioxide forming green copper carbonate.

c) Aluminium oxide is called amphoteric because it reacts with both acids and bases.

d) Hydrogen gas is not released with concentrated nitric acid because nitric acid is a strong oxidizing agent and forms nitrogen oxides instead of hydrogen.

Formation of Magnesium Chloride (MgCl₂) using electron dot structure:

Mg → Mg²⁺ + 2e⁻
Cl + e⁻ → Cl⁻

Magnesium loses two electrons and each chlorine atom gains one electron.

Mg²⁺ + 2Cl⁻ → MgCl₂

5 Mark Questions

State the difference between annealing and roasting. How are these processes used in the extraction of zinc? Explain with equations. Is reduction necessary to obtain zinc after these processes? Why?
(April 2020 / MQP 2025)
a) Explain the formation of an ionic bond between sodium and chlorine atoms.
(Sodium atomic number: 11, Chlorine atomic number: 17) (June 2022 / MQP 2025)
b) List any four common features of ionic compounds. (MQP 2025)

5 Mark Answer Key

Difference between Roasting and Calcination (Annealing):

Roasting	Calcination (Annealing)
Heating of sulphide ores in the presence of excess air.	Heating of carbonate or hydrated ores in the absence or limited supply of air.
Converts sulphide ores into oxides.	Removes moisture and converts carbonates into oxides.
Sulphur is removed as sulphur dioxide (SO₂).	Carbon dioxide (CO₂) or water vapour is removed.

Extraction of Zinc:

Zinc is commonly extracted from zinc blende (ZnS).

Step 1: Roasting
2ZnS + 3O₂ → 2ZnO + 2SO₂

If zinc carbonate (ZnCO₃) is present, it undergoes calcination:
ZnCO₃ → ZnO + CO₂

Thus, both processes convert the ore into zinc oxide (ZnO).

Step 2: Reduction
ZnO + C → Zn + CO

Is reduction necessary?
Yes. After roasting or calcination, zinc is present as zinc oxide (ZnO). To obtain pure zinc metal, ZnO must be reduced by carbon because zinc cannot be obtained directly from its oxide without reduction.

a) Formation of Ionic Bond between Sodium and Chlorine:

Atomic number of Sodium (Na) = 11
Electronic configuration = 2, 8, 1

Atomic number of Chlorine (Cl) = 17
Electronic configuration = 2, 8, 7

Sodium has one valence electron and tends to lose it to attain stable octet configuration.
Na → Na⁺ + e⁻

Chlorine needs one electron to complete its octet.
Cl + e⁻ → Cl⁻

The electron lost by sodium is gained by chlorine forming Na⁺ and Cl⁻ ions. The strong electrostatic force of attraction between oppositely charged ions forms an ionic bond.

Na⁺ + Cl⁻ → NaCl

b) Four common features of ionic compounds:
1. They are generally hard and crystalline solids.
2. They have high melting and boiling points.
3. They are soluble in water but insoluble in organic solvents.
4. They conduct electricity in molten state or aqueous solution but not in solid state.