Nitrogen oxides produced from the emission of automobiles and power plants are the source of fine airborne particles which lead to:

What is polluted by chemically synthesized pesticides?

In agriculture,improper drainage of water leads to:
$I-$ The soil becomes waterlogged.
$II -$ The soil surface draws up salts from the water.
$III -$ Salts are deposited as a thin crust on the land surface.
$IV -$ Salts start accumulating around the roots of the plants.
$V -$ The increasing concentration of salts becomes favorable for crop growth.
$VI -$ It is highly beneficial for agriculture.
Which of the above statements are correct?

What is $B.O.D$?

In catalytic converters,.......... metal is used as a catalyst.

Identify the colloidal materials present in domestic sewage.