Most hazardous pollutant of automobile exhaust is

$A$ lake with an inflow of domestic sewage rich in organic waste may result in:

The pollutants which are already present in nature,but are released in substantial amounts by man are known as

What is the effect of $DDT$ in birds?

Acid rain is caused due to an increase in the concentration of which of the following in the atmosphere?

Assertion $(A)$: Pollution is always caused by human activities.
Reason $(R)$: Pollution is not different from contamination.