In municipal sewage,$BOD$ values (in $ppm$) are

Water filled in two glasses $A$ and $B$ have $BOD$ values of $10$ and $20$ respectively. The correct statement regarding them is:

Which of the following is not an air pollutant?

Observe the following statements:
Statement-$I$: The carbon-containing components of photochemical smog are acrolein,methanal,and $PAN$.
Statement-$II$: The number of greenhouse gases in the list given below is $5$: $CH_4, CO_2, NO, H_2O_{(l)}, H_2O_{(g)}, O_2, O_3$.
The correct answer is:

Write down the effect of particulate pollutants on the environment.

Green chemistry means such reactions which