1. What is the chemical process in which a substance reacts with oxygen to give off heat?

• Combustion
• Photosynthesis
• Respiration
• Oxidation

2. Which gas is necessary for combustion?

• Oxygen
• Nitrogen
• Carbon dioxide
• Hydrogen

3. Which of the following is not a combustible substance?

• Glass
• Paper
• Wood
• Kerosene

4. Which zone of a candle flame is the hottest?

• Blue zone
• Dark zone
• Luminous zone
• Outer zone

5. Which of these is used as a fuel in jet aircrafts?

• Kerosene
• Petrol
• Diesel
• LPG

6. What is the term for a fuel that leaves no residue after burning?

• Clean fuel
• Smokeless fuel
• Ideal fuel
• Efficient fuel

7. Which gas is produced due to incomplete combustion of fuels?

• Carbon monoxide
• Carbon dioxide
• Methane
• Oxygen

8. The ignition temperature of a substance is the:

• Minimum temperature to catch fire
• Melting point
• Boiling point
• Combustion rate

9. Which instrument is used to measure calorific value?

• Bomb calorimeter
• Thermometer
• Manometer
• Barometer

10. Which of the following fuels has the highest calorific value?

• Hydrogen
• Petrol
• Coal
• Wood

11. Which part of the candle flame is least hot?

• Dark zone
• Luminous zone
• Non-luminous zone
• Blue zone

12. What is the typical ignition temperature of paper?

• Around 233°C
• Around 100°C
• Around 500°C
• Around 80°C

13. Which zone of the flame produces soot?

• Luminous zone
• Dark zone
• Non-luminous zone
• Blue zone

14. Which of these is not a characteristic of an ideal fuel?

• High ignition temperature
• High calorific value
• No residue
• Low cost

15. What is a spontaneous combustion example?

• White phosphorus catching fire in air
• Candle burning
• LPG stove
• Matchstick lighting

16. Which category does petrol fall into based on its ignition temperature?

• Highly inflammable
• Moderately inflammable
• Non-combustible
• Thermal insulator

17. Which of the following is used in fire extinguishers?

• Carbon dioxide
• Oxygen
• Hydrogen
• Nitrogen

18. Which zone of flame is used by goldsmiths for melting metals?

• Non-luminous zone
• Luminous zone
• Dark zone
• Red zone

19. Which of these is a solid fuel?

• Wood
• Petrol
• Diesel
• CNG

20. What is the calorific value of LPG approximately?

• 55,000 kJ/kg
• 4,000 kJ/kg
• 25,000 kJ/kg
• 20,000 kJ/kg

21. Which of these does not support combustion?

• Carbon dioxide
• Oxygen
• Air
• Hydrogen peroxide

22. Which flame zone appears yellow?

• Luminous zone
• Non-luminous zone
• Blue zone
• Dark zone

23. Which of the following materials catches fire most easily?

• Petrol
• Charcoal
• Iron rod
• Coal

24. What happens during complete combustion?

• Only carbon dioxide is formed
• Soot is released
• Carbon monoxide is formed
• Sulphur is produced

25. Why is water not used to extinguish fires caused by electrical equipment?

• It conducts electricity
• It increases fire
• It evaporates quickly
• It reacts with fuel

26. What is an example of rapid combustion?

• Burning of cooking gas
• Rusting of iron
• Lighting of firefly
• Spontaneous fire in coal mine

27. What is left behind after the combustion of magnesium ribbon?

• White ash
• Black soot
• Liquid metal
• Carbon powder

28. What is the role of the wick in a candle?

• Absorbs and delivers melted wax
• Creates oxygen
• Produces light
• Forms the dark zone

29. Which component in air helps in burning?

• Oxygen
• Nitrogen
• Carbon dioxide
• Argon

30. Which chemical reaction is involved in combustion?

• Exothermic reaction
• Endothermic reaction
• Neutralization
• Displacement reaction

31. In which flame zone is wax vapor broken down into simpler substances?

• Luminous zone
• Dark zone
• Non-luminous zone
• Base zone

32. What does the calorific value of fuel indicate?

• Energy released per kg
• Ignition point
• Smoke quantity
• Efficiency of combustion

33. Why is biogas considered a clean fuel?

• No smoke or harmful gases
• It is cheap
• It is heavier
• It is available in cylinders

34. Which of these flames is suitable for welding?

• Blue flame
• Yellow flame
• Red flame
• Smoky flame

35. What is a fire triangle composed of?

• Fuel, heat, oxygen
• Fuel, water, CO2
• Smoke, spark, fuel
• Ash, heat, air

36. Which of the following is an indicator of incomplete combustion?

• Presence of carbon monoxide
• High flame
• Loud sound
• Water vapor

37. Why do metals not catch fire easily?

• High ignition temperature
• Soft nature
• High density
• High conductivity

38. What is observed when a matchstick is struck?

• Friction causes ignition
• Cooling occurs
• Combustion stops
• Soot forms immediately

39. Which of the following is used in gas lighters?

• Piezoelectric crystal
• Flint
• Magnet
• Mercury cell

40. Which is more environmentally friendly: LPG or coal?

• LPG
• Coal
• Both equal
• Depends on usage