In India,the most commonly used pesticide $BHC$ is

Which are the primary constituents of photochemical smog?

Which of the following steps can be taken to control global warming?
$I-$ Reducing the use of fossil fuels.
$II-$ Improving energy efficiency.
$III-$ Deforestation.
$IV-$ Afforestation.
$V-$ Increasing human population growth.

The pollution in a city like $Delhi$ may be controlled to a great extent by:

Which of the following sources of energy is non-renewable?

The figure shows the biomagnification of $DDT$ in an aquatic food chain. What could be the concentration of $DDT$ in $P$,$Q$,and $R$ respectively?