Oxygen of the air is utilized for 'combustion' and for 'respiration'. Compare the two with a suitable example.

State the utility of carbon dioxide for manufacture of food by plants. State its role in warming the earth's environment and in excess resulting in global warming.

Give the environment effect of three polluting gases with a reason why nitrogen is not considered a polluting gas.

Describe simple experiment to show the presence of oxygen and nitrogen component in air using a bell jar.