### Theory:

Air is a mixture of gases. It is essential for the survival of all living organisms.
Humans breathe in oxygen ($$O_2$$) and breathe out carbon dioxide ($$CO_2$$). Whereas plants use carbon dioxide for photosynthesis and release oxygen into the atmosphere.

Humans breath in $$O_2$$ and breath out $$CO_2$$;

Plants release $$O_2$$ and absorbs $$CO_2$$

Note: The process of bringing oxygen to our body by lungs is called inspiration or inhalation. Expiration or exhalation, on the other hand, is the process of sending carbon dioxide out through the lungs.

Composition of air:

Air is composed of nitrogen ($$N_2$$), oxygen ($$O_2$$), argon ($$Ar$$), carbon dioxide ($$CO_2$$) and a small amount of other gases.

Composition of air

What is the reason for the high temperature in the atmosphere?

High temperature

Humans are cutting the trees for their needs, so the level of carbon dioxide is increasing in the atmosphere. This is the reason for the rising temperature in the atmosphere.

How do human activities cause global warming and acid rain?

Global warming and acid rain

Industries and vehicles release carbon monoxide ($$CO$$), sulphur dioxide ($$SO_2$$) and nitrogen oxides ($$NO_x$$) into the atmosphere. These air pollutants react with water, oxygen and other substances to produce airborne sulphuric acid ($$H_2SO_4$$) and nitric acid ($$HNO_3$$). This result in global warming, acid rain and the greenhouse effect.
Reference:
https://th.bing.com/th/id/R.8116c64629c2fa49e41879e3504619bb?rik=Z9iHfSkDJJAMvg&riu=http%3a%2f%2fpubs.sciepub.com%2fajfn%2f6%2f1%2f3%2fimage%2ffig1.png&ehk=53tcZ2B3OoAkFJvpnl32J01csgjU%2fAwzI8s%2biqTTa%2b0%3d&risl=&pid=ImgRaw&r=0