Which of the following industries produce phenolic compounds and suspended solids as waste?

Match List-$I$ with List-$II$

List-$I$ Industry	List-$II$ Waste Generated
$A$. Steel plants	$I$. Gypsum
$B$. Thermal power plants	$II$. Fly ash
$C$. Fertilizer industries	$III$. Slag
$D$. Paper mills	$IV$. Bio-degradable Wastes

Choose the correct answer from the options given below:

$A$ water sample is considered the cleanest based on which of the following $BOD$ values (in $ppm$)?

Statues and monuments in India are affected by acid rain. How?

Match the water pollutants given in List-$I$ with their sources given in List-$II$.

List-$I$	List-$II$
$A$. Toxic heavy metals	$1$. Soil erosion from agricultural and mineral industries.
$B$. Pesticides	$2$. Domestic sewage disposal.
$C$. Sediments	$3$. Chemical factories and industries.
$D$. Microorganisms	$4$. Substances used to kill insects,fungi,and weeds.

The pollutants which come directly into the air from sources are called primary pollutants. Primary pollutants are sometimes converted into secondary pollutants. Which of the following belongs to secondary air pollutants?