Fly-ash is a/an :

Due to biomagnification,if the concentration of $DDT$ in water is $0.003 \, ppm$,what will be the concentration of $DDT$ in zooplankton,small fish,large fish,and fish-eating birds,respectively?

$SO_{2}$ pollution is indicated by

The noise produced in an office is normally at the level of: (in $\text{ dB}$)

The electrostatic precipitator can remove over . . . . . . particulate matter. (in $;\%$)

It refers to the amount of oxygen that would be consumed if all the organic matter in one liter of water were oxidized by bacteria.