Need for Air in Fire

Q.

Which of the following are natural chemical changes?

1. Respiration
2. Photosynthesis
3. Explosion of fire works
4. Combustion of fuels

Q.

State three uses of oxygen, other than artificial respiration.

Q.

___ gas is evolved upon combustion of an organic substance along with water vapour.

Q.

Fill in the blanks to complete the analogy:

Hydrogen: Burns in air; Oxygen: __________

Q.

Air doesn't support burning.

1. True

2. False

Q.

Air supports burning.

1. False

2. True

Q. Among the gases present in air, which one supports burning of a substance?

1. Oxygen
2. Carbon dioxide
3. Nitrogen
4. Water vapour

Q. Air, containing oxygen, is present all around us. We know that oxygen supports burning. So logically, in the presence of oxygen, even a small fire should burn down everything.

1. True
2. False

Q.

Sometimes, when a person is caught with fire, a thick blanket is wrapped around him or her. This is done to

1. cut off the oxygen supply.

2. keep the body cool.

3. cut off the inert gases supply.

4. cut off the nitrogen supply.