CHAPTER 6 AIR AROUND US
Air is simply a mixture of gases and dust particles. All living things need air. Humans and animals need it to breathe and plants need it for photosynthesis. Air is everywhere around you even if you think it isn’t. Even an empty bottle is not empty. It is filled with air.
Constituents of air
1. Water vapour
Air contains water vapour. The water that evaporates from water bodies or is released by plants through transpiration, reaches the atmosphere, as we’ve studied before. Water vapour in air is an important part of the water cycle.
Oxygen is vital for all living things for respiration. Oxygen is also necessary for burning. Plants replenish the oxygen in the atmosphere through photosynthesis. During photosynthesis, plants give out oxygen.
About 78% of the earth’s atmosphere is nitrogen. Nitrogen does not support burning.
4. Carbon dioxide
Plants and animals consume oxygen and give out carbon dioxide. The process of burning also releases carbon dioxide.
5. Dust and smoke
Smoke is a mixture of gases and dust particles which can be harmful. Dust particles are always present in some quantity in the air.
Oxygen and Nitrogen together make up 99% of the atmosphere. The remaining 1% contains Carbon Dioxide, other gases, water vapour and dust particles. Air is also dissolved in water and is also present in soils in the burrows and holes that animals (like rabbits) dig.
Air is, without a doubt, the most necessary prerequisite for living things to survive.
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