Contour farming is usually employed in

Approximately $P$ fraction of the solar radiation reaching the Earth is reflected by clouds and gases,and another $Q$ fraction is absorbed by them.

Match the following.

Column-$I$	Column-$II$
$(p)$ Increasing level of $CO_2$	$(i)$ Ozone depletion
$(q)$ $CFC$	$(ii)$ Antarctica region
$(r)$ Ozone hole	$(iii)$ Greenhouse effect
$(s)$ $UV$ rays	$(iv)$ Senescence of skin

In which state/country are Ecosan toilets not found?

If an agricultural field is liberally irrigated for a prolonged period of time,it is likely to face the problem of:

At the beginning of the twentieth century,forests covered about ....... of the land of India. By the end of the century,it shrunk to.......