What is the ascending order of $BOD$ for the following: Sewage $(S)$,Paper mill effluent $(PE)$,Distillery effluent $(DE)$,and Sugar factory effluent $(SE)$?

Where was the attempt to treat wastewater by combining artificial and natural processes carried out?

Reduction in soil fertility due to erosion is an example of

$A$: High concentration of atmospheric $SO_2$ and $NO_x$ causes acid rain.
$R$: It causes damage to foliage and growing points of plants.

Match the following important dates/events related to environmental issues in India:
$A$. $2002$
$B$. $1$ April $2005$
$I$. Bharat Stage $II$ applicable to all automobiles in the country.
$II$. All buses of Delhi were converted to run on $CNG$.

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