Jet aircrafts fly in the :

The mixture  of gases  that makes up the Earth's atmosphere is called:

Air supplies us with:

What is added to water to attract dirt particles?

What is the process of purifying water by first boiling  and then condensing called? 

Removing impurities by passing water through a thin cloth or filter paper is called:

How long should water be boiled to kill germs?

In how many forms is  water present in nature?

Which gas present in the atmosphere helps plants to prepare their food?

Presence of which gas in air makes respiration possible ?