The maximum prescribed concentration of copper in drinking water is ........ $ppm$.

Rain water is called as acid rain when its $pH$ is below

What are the reactions involved in the ozone layer depletion in the stratosphere?

$A$ water sample has $ppm$ level concentration of following anions:
$F^- = 10; \, SO_4^{2-} = 100; \, NO_3^- = 50$
The anion/anions that make/makes the water sample unsuitable for drinking is/are:

Peroxyacetyl nitrate $(PAN)$,an eye irritant,is produced by:

Given below are two statements.
Statement $I:$ In polluted water,values of both dissolved oxygen and $BOD$ are very low.
Statement $II:$ Eutrophication results in a decrease in the amount of dissolved oxygen.
In the light of the above statements,choose the most appropriate answer from the options given below.