Photochemical smog does not contain .....

$DDT$ residues are rapidly passed through the food chain causing biomagnification because $DDT$ is:

In an aquatic food chain,if a water body has $0.003 \; ppb$ of $DDT$,its maximum concentration can be observed in:

$A$: $Euro-II$ norms were framed to reduce the content of $CO$ and aromatic compounds from fuels.
$R$: These compounds lead to reduced visibility and carboxyhemoglobin formation.

Foul smell in the water bodies of tanks,ponds,etc.,is due to:

The $BOD$ limit prescribed by the Central Pollution Control Board $(CPCB)$ for the discharge of industrial and municipal wastewater into natural surface water bodies is .....