Extra 40 MCQ questions and answers from the chapter:4 "Combustion and Flame" for Class 8 Science (CBSE):-

1. Which of the following is necessary for combustion?

a) Carbon dioxide
b) Nitrogen
c) Oxygen
d) Hydrogen
Ans: c) Oxygen

 

2. The substances that catch fire easily are called:

a) Non-combustible substances
b) Inflammable substances
c) Fireproof substances
d) Conductors
Ans: b) Inflammable substances

 

3. Which of the following is a good fuel?

a) Wood
b) Kerosene
c) Petrol
d) LPG
Ans: d) LPG

 

4. The lowest temperature at which a substance catches fire is called:

a) Ignition temperature
b) Boiling point
c) Melting point
d) Freezing point
Ans: a) Ignition temperature

 

5. Which gas is necessary for combustion?

a) Carbon dioxide
b) Oxygen
c) Nitrogen
d) Argon
Ans: b) Oxygen

 

6. Which of the following does NOT burn with a flame?

a) Wood
b) Kerosene
c) Charcoal
d) Paper
Ans: c) Charcoal

 

7. Which part of a candle flame is the hottest?

a) Dark inner zone
b) Luminous zone
c) Non-luminous outer zone
d) Blue zone
Ans: c) Non-luminous outer zone

 

8. What type of combustion takes place in a matchstick when rubbed against a rough surface?

a) Spontaneous combustion
b) Rapid combustion
c) Explosion
d) Slow combustion
Ans: b) Rapid combustion

 

9. The substance that undergoes combustion is called:

a) Flame
b) Fuel
c) Gas
d) Fire
Ans: b) Fuel

 

10. Which type of combustion does NOT produce a flame?

a) Wood burning
b) LPG burning
c) Coal burning
d) Kerosene burning
Ans: c) Coal burning

 

11. Which of the following fuels is the most environment-friendly?

a) Coal
b) Diesel
c) CNG
d) Wood
Ans: c) CNG

 

12. What does a fire extinguisher mainly remove to put out a fire?

a) Fuel
b) Oxygen
c) Ignition temperature
d) Smoke
Ans: b) Oxygen

 

13. Which part of a flame is used in welding metals?

a) Dark zone
b) Luminous zone
c) Non-luminous outer zone
d) Inner zone
Ans: c) Non-luminous outer zone

 

14. The color of the hottest part of a flame is:

a) Blue
b) Yellow
c) Red
d) Orange
Ans: a) Blue

 

15. Which fuel is commonly used for cooking in rural areas?

a) LPG
b) Biogas
c) Kerosene
d) Petrol
Ans: b) Biogas

 

16. Which of these is NOT a fossil fuel?

a) Petrol
b) Charcoal
c) Coal
d) Natural gas
Ans: b) Charcoal

 

17. What type of combustion occurs when petrol catches fire instantly?

a) Slow combustion
b) Rapid combustion
c) Spontaneous combustion
d) Explosion
Ans: b) Rapid combustion

 

18. Which gas is produced in large amounts when fossil fuels burn?

a) Oxygen
b) Carbon dioxide
c) Hydrogen
d) Nitrogen
Ans: b) Carbon dioxide

 

19. Which is the best fuel for vehicles in terms of pollution control?

a) Petrol
b) Diesel
c) CNG
d) Coal
Ans: c) CNG

 

20. The flame of a candle has three zones. Which one is the hottest?

a) Inner zone
b) Middle zone
c) Outer zone
d) None of these
Ans: c) Outer zone

 

21. Which of these is NOT a characteristic of an ideal fuel?

a) High calorific value
b) Produces large amounts of ash
c) Environmentally friendly
d) Easily available
Ans: b) Produces large amounts of ash

 

22. What is the main component of LPG?

a) Methane
b) Ethane
c) Butane
d) Carbon dioxide
Ans: c) Butane

 

23. Which substance has the highest ignition temperature?

a) Wood
b) Petrol
c) Kerosene
d) Paper
Ans: a) Wood

 

24. The fuel used in rocket engines is:

a) Diesel
b) Petrol
c) Hydrogen
d) LPG
Ans: c) Hydrogen

 

25. What is the primary cause of global warming?

a) Oxygen
b) Carbon dioxide
c) Nitrogen
d) Helium
Ans: b) Carbon dioxide

 

26. Which of the following is a solid fuel?

a) Petrol
b) Diesel
c) Coal
d) LPG
Ans: c) Coal

 

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

a) Carbon monoxide
b) Oxygen
c) Nitrogen
d) Hydrogen
Ans: a) Carbon monoxide

 

28. Which of the following is a non-combustible substance?

a) Paper
b) Wood
c) Glass
d) Petrol
Ans: c) Glass

 

29. The process of burning a substance in the presence of oxygen is called:

a) Rusting
b) Combustion
c) Evaporation
d) Condensation
Ans: b) Combustion

 

30. Why does water extinguish fire?

a) Lowers ignition temperature
b) Increases oxygen supply
c) Forms a protective layer
d) Absorbs heat and reduces temperature
Ans: d) Absorbs heat and reduces temperature

 

31. Which fuel is commonly used in jet aircraft?

a) Diesel
b) Kerosene
c) LPG
d) Petrol
Ans: b) Kerosene

 

32. The fuel used in thermal power plants is:

a) Wood
b) Coal
c) LPG
d) Petrol
Ans: b) Coal

 

33. Why is carbon monoxide dangerous?

a) It has a bad smell
b) It is highly flammable
c) It is poisonous and reduces oxygen in blood
d) It is colorless
Ans: c) It is poisonous and reduces oxygen in blood

 

34. What is the primary fuel used in rural households?

a) LPG
b) Kerosene
c) Wood
d) CNG
Ans: c) Wood

 

35. The calorific value of a fuel is measured in:

a) Joules
b) Calories
c) kJ/kg
d) Watts
Ans: c) kJ/kg

 

36. Which of the following fuels is smokeless?

a) Wood
b) LPG
c) Charcoal
d) Coal
Ans: b) LPG

 

37. Fire extinguishers mainly contain:

a) Oxygen
b) Carbon dioxide
c) Hydrogen
d) Nitrogen
Ans: b) Carbon dioxide

 

38. Which is the most polluting fossil fuel?

a) Coal
b) Petrol
c) Diesel
d) LPG
Ans: a) Coal

 

39. Which fuel is used in candles?

a) Paraffin wax
b) Diesel
c) LPG
d) Petrol
Ans: a) Paraffin wax

 

40. Which zone of a candle flame is dark?

a) Inner zone
b) Middle zone
c) Outer zone
d) None of these
Ans: a) Inner zone