Which of the following is not a greenhouse gas $(GHG)$?

Which region of the atmosphere is the domain of all living organisms?

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.

Fill in the blanks:
$(1)$ The types of smog are ..... and ..... .
$(2)$ Ozone in the air reacts with hydrocarbons to form ...... and ...... .
$(3)$ Harmful ultraviolet rays from the sun cause a type of skin cancer known as ...... .
$(4)$ Chlorofluorocarbon compounds are also called .......... .

Identify the coldest region among the following layers of atmosphere.

Excess nitrate in drinking water can cause