What is the name of the process in which rain water falling on the earth is stopped from flowing and made to percolate into the ground ?

Which fossil fuel is conserved :

(a) when we save on electricity?

(b) when we use bicycle for covering short distances instead of a motorbike ?

What is the main purpose of rainwater harvesting ?

Name the most common practice of recharging ground water.

The pH of a river water sample as measured by pH paper is found to be What does it tell us about water?