Which of the following methods can be used to control water pollution?

The delicate balance of $CO_2$ and $O_2$ is $NOT$ disturbed by:

Which of the following is the most significant air pollutant in modern times?

Which of the following statements are correct?
$A$. Ocean is a sink for $CO_2$.
$B$. Greenhouse effect causes lowering of the temperature of the earth's surface.
$C$. To control $CO$ emission by automobiles,usually catalytic converters are fitted into exhaust pipes.
$D$. $H_2SO_4$,herbicides,and insecticides form mist.

The presence of which of the following substances in flue gases is the best indicator of incomplete combustion of petrol or diesel in an automobile engine?

How can domestic waste be used as manure?