CHEMISTRY [2 Mark Question Answer]

Trees absorb carbon dioxide during photosynthesis to make their own food. Carbon-dioxide in excess amount in air is a major air pollutant causing global warming and other damages. Planting more trees would mean more absorpti on of carbon dioxide by them and hence less air pollution.

The process,by which iron gets covered with reddish-brown flaky substance (rust) in the presence of moist air is called rusting of iron. Conditions required for rusting are:
1. Presence of air (or oxygen)
2. Presence of water (or moisture)

Fuels bum to produce energy in the form of heat and light.
Carbon-dioxide and water vapour are released as by products.

Component of air – Percentage by volume
Nitrogen – 78 per cent
Oxygen – 21 per cent
Carbon dioxide – 0.02-0.03 per cent
Inert gases – about 0.9 per cent
Water vapour – variable
Dust particles – variable
Impurities – variable