The periodic change in temperature in the Pacific Ocean is known as .............

Match the items in Column $A$ with those in Column $B$:
\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau\tau

Column $A$	Column $B$
$(A)$ Catalytic converter	$(i)$ Particulate matter
$(B)$ Electrostatic precipitator	$(ii)$ Carbon monoxide and nitrogen oxides
$(C)$ Earmuffs	$(iii)$ High noise level
$(D)$ Landfills	$(iv)$ Solid waste

According to a $1990$ report,Delhi ranked $........$ among the $41$ most polluted cities in the world.

Domestic sewage mainly contains $A$ wastes which are readily decomposed with the help of $B$. Here $A$ and $B$ refer to:

Reduction in soil fertility due to erosion is an example of

Which of the following statements regarding pollutants is correct?