CBSE Class 8: Solved Multiple Choice Questions Science (combustion and flame)

1. Which fuels are used for running automobiles?
a. Wood
b. Coal
c. Diesel
d. Charcoal
Ans. 1. (c)

2. When magnesium ribbon burnt it produce
a. Magnesium hydroxide
b. Magnesium oxide
c. Magnesium chloride
d. Magnesium sulphate
Ans.2. (b)

3. Charcoal burns in air producing-
a. CO2
b. CO
c. H2
d.O2
Ans.3. (a)

4. Combustion is a reaction in which a Substance reacts with-
a. Hydrogen
b. Nitrogen
c. Oxygen
d. Chlorine
Ans. 4. (c)

5. Fuel may be-
a. Solid
b. Liquid
c. Gas
d. All of these
Ans. 5. (d)

6 Which one of the following is fuel of our body?
a. Petrol
b. Diesel
c. Food
d. Water
Ans. 6. (c)

7. Combustion is a-
a. Physical process
b. Chemical process
c. Both (a) & (b)
d. None of these
Ans.7. (b)

8 Which one of the following is combustible?
a. Iron nail
b. Glass
c. Stone pieces
d. Paper
Ans.8. (d)

9. The lowest temperature at which a Substance catches fire is called its-
a. Boiling point
b. Melting point
c. Ignition temperature
d. Critical temperature
Ans.9(c)

10. Which of the following has lower ignition temperature?
a. Wood
b. Paper
c. Vegetable oil
d. Kerosene oil
Ans.10. (d)

11. Which one of the following is non Combustible?
a. Stone piece
b. Paper
c. Straw
d. Matchsticks
Ans.11. (a)

12. In the presence of water, ignition Temperature of paper is-
a. Decrease
b. Increase
c. Remain constant
d. None of these
Ans. 12. (a)

13. Which of the following is inflammable Substances?
a. Petrol
b. Wood
c. Paper
d. Straw
Ans.13. (a)

14. Essential requirements for producing fire are:
a. Fuel
b. Air
c. Heat
d. All of these
Ans.14. (d)

15. Fire extinguisher-
a. Cut off the supply of air
b. Bring down the temperature of fuel
c. Both (a) & (b)
d. None of these
Ans.15. (c)

16. For combustion ________is necessary
a. Air
b. Water
c. Paper
d. Fuel
Ans.16. (a)

17. Rapid combustion is
a. When gas burns, it produces heat and light
b. When material suddenly burst into flames
c. When there is evolution of heat
d. None of these
Ans.17. (a)

18. Explosion is the evolution of
a. Heat
b. light
c. Sound
d. All of these
Ans.18. (d)

19. Substance which vaporise during Burning gives
a. Sound
b. Flame
c. Combustion
d. None of these
Ans. 19. (b)

20. Which is the hottest part in the flame of the candle
a. Blue
b. Yellow
c. Black
d. Wax part
Ans. 20 (a)

21. Innermost zone is the
a. Hottest part
b. Moderately hot part
c. Least hot part
d. Cold part
Ans. 21. (c)

22. Yellow colour in the flame denotes
a. Outermost part
b. Middle zone
c. Innermost zone
d. None of these
Ans.22. (b)

23. Good fuel is
a. Readily available
b. Cheap
c. Burn easily in air
d. All of these
Ans.23. (d)

24. On burning fuel produces..... amount of heat
a. Large
b. Less
c. Very less
d. No heat
Ans.24. (a)

25. Which is better domestic fuel
a. CNG
b. LPG
c. Wood
d. Coal
Ans.25. (b)

26. Use of ..... in vehicle reduces pollution
a. Petrol
b. Diesel
c. CNG
d. None of these
Ans.26. (c)

27. During the process of combustion ________is given out
a. Heat
b. Light
c. Sound
d. Both heat & light
Ans. 27. (d)

28. The most common fire extinguisher is
a. Water
b. CO2
c. Oxygen
d. Hydrogen
Ans.28. (a)

29. Ideal fuel has ____ calorific value
a. Low
b. High
c. Moderate
d. Zero
Ans. 29. (b)

30. Calorific value gives the
1.Fuel efficiency
2.Amount of heat
3.Amount of light
4.None of these
Ans.30. (a)

31. Calorific value is measured in
a. Kilo joule
b. Kilograms
c. Kilo joule per Kg
d. Kilometre
Ans.31. (c)

32. Unburnt carbon particles causes
a. Stomach infections
b. Respiratory problems
c. Brain infections
d. Throat problems
Ans. 32. (b)

33. Incomplete combustion gives
a. CO2
b. CO
c. Carbon
d. None of these
Ans.33. (b)

34. Goldsmith uses ____part of the flame for melting gold
a. Outermost
b. Middle
c. Innermost
d. Both (b) & (c)
Ans. 34. (a)

35. Amount of heat energy produced on _____combustion of 1kg of fuel is Calorific value
a. Incomplete
b. Complete
c. Half
d. None of these
Ans. 35. (b)

36. Element showing spontaneous combustion is
a. Calcium
b. Phosphorous
c. Lithium
d. Copper
Ans.c

37. Which of the following is/are carbon fuel
a. Wood
b. Coal
c. Petroleum
d. All of these
Ans.) 37. (d)

38. Combustion of most fuels releases
a. CO2
b. SO2
c. NO2
d. Oxygen
Ans.38. (a)

39. Global warming is caused due to____ concentration of Co2 in air
a. Decreased
b. Increased
c. Both (a) & (b)
d. None of these
Ans.39. (b)

40. Burning of coal and diesel releases
a. NO2
b. CO2
c. SO2
d. CO
Ans.40. (c)

1.Petrol engine gives off gaseous oxides of
a. Sulphur
b. Nitrogen
c. Phosphorous
d. Carbon
Ans.41. (b)

42. Acid rain is caused by oxides of
a. Sulphur, Nitrogen
b. Sulphur, Carbon
c. Carbon, Nitrogen
d. Phosphorous, Carbon
Ans. 42. (a)

43. Which is a solid fuel?
a. Petrol
b. Diesel
c. Wax
d. Wood
Ans.43. (c)

44. In the sun, heat and light are produced by
a.Chemical reactions
b.Nuclear reactions
c.Ionic reactions
d.None of these
Ans.44. (b)

45. The head of the safety match contains
a. Antimony trisulphide
b Potassium Chlorate
c. Both (a) and (b)
d. None of these
Ans.45. (c)

46. When the match struck against rubbing surface, red phosphorous
a. Converts into white phosphorous
b. Reacts with potassium chlorate
c. Ignite antimony trisulphide
d. None of these
Ans.46. (a)

47. Best extinguisher for inflammable Materials is
a. Water
b. SO2
c. CO2
d. CO
Ans.47. (c)

48 CO2 is stored as a liquid in cylinder at
a. High pressure
b. Low pressure
c. High temperature
d. Low temperature
Ans.48. (a)

49. CO2 is given off by chemicals like
a. Sodium bicarbonate
b. Calcium sulphate
c. Sodium sulphate
d. Sulphuric acid
Ans. 49. (a)

50. Water is not suitable for fire involving
a. Oil
b. Petrol
c. Both (a) & (b)
d. None of these
Ans. 50. (c)