Question

c) The temperature of burning substance d) The temperature in the substance when fire if put off 10. Explosion takes place because of a) Release of large amount of gas under pressure due to sudden reaction b) Release of large amount of heat c) Release of large amount of light d) None of the above 11. What is the main chemical component present in striking surface of a matchbox? A. Potassium chlorate B. Phosphorus C. Potassium D. Graphite 12. The efficiency of a fuel is expressed in terms of its ________. A. density B. calorific value C. volume D. purity 13. The SI unit of the calorific value of a fuel is :- A. N/kg B. KJ/kg C. KW/kg D. J/kg 14. Which substance give heat and light after combustion a. Flame b. Fuel c. Combustion d. None of these 15. Like fuel the sun also provides heat and light. The process taking place in the sun is calleda. Combustion

b. Nuclear process

c. Burning

d. All of these

16. Coal burns with ______

a. Flame

b. Only glow

c. Both flame and glow

d. None of these

17. Burning of charcoal in a closed room will produce

a. Carbon dioxide

b. Nitrogen dioxide

c. Carbon monoxide

d. All of these

18. Goldsmith uses ____part of the flame for melting gold

a. Outermost

b. Middle

c. Innermost

d. Both (b) & (c)

19. Amount of heat energy produced on _____combustion of 1kg of fuel is Calorific value

a. Incomplete

b. Complete

c. Half

d. None of these

20. Combustion of most fuels releases

a. CO2

b. SO2

c. NO2

d. Oxygen

21. Global warming is caused due to____ concentration of Co2 in air

a. Decreased

b. Increased

c. Both (a) & (b)

d. None of these

22. Acid rain is caused by oxides of

a. Sulphur, Nitrogen

b. Sulphur, Carbon

c. Carbon, Nitrogen

d. Phosphorous, Carbon
Question 1.

What does magnesium burn to form?

Question 2.

What does coal produce during its combustion?

Question 3.

What is combustion?

Question 4.

Define ignition temperature of a fuel.

Question 5.

How does a matchstick catch fire?

Question 6.

What are combustible and non-combustible substances?

Question 7.

What are inflammable substances? Give examples.

Question 8.

What is rapid combustion?

Question 9.

Define spontaneous combustion.

Question 10.

What is the composition of the head of a matchstick?

Question 11.

Mention any three characteristics of a good fuel.

Question 12.

What is global warming?​

Answer 1

Explanation:

(b) produces a large amount of heat. (c) leaves behind many undesirable substances. (d) burns easily in the air at a moderate rate