Earth's atmosphere has mainly five layers as
exosphere, thermosphere, mesosphere, stratosphere and troposphere. The
composition of atmosphere is 78 % of N₂,
21 % of O₂, 1 % of Ar and rest
is CO₂ and trace gases.
Earth's atmosphere helps to make suitable conditions for living things by
1. blocking harmful uv rays by ozone
layer
2. trapping heat to maintain the temperature on
Earth's surface
3. having O₂ gas for breathing of living things
4. having CO₂ gas which is used to make foods by
photosynthesis
5. creating pressure on Earth's
surface to keep water in its liquid form.