Give the names of greenhouse gases.

Identify the correct statements from the following:
$i$. In the presence of $UV$ light,$CF_2Cl_2(g)$ gives chlorine free radicals which will react with $O_3(g)$ to form $O_2(g)$.
$ii$. Drinking water with $10 \ ppm$ fluoride is better than drinking water with $1 \ ppm$ fluoride.
$iii$. The maximum permissible concentration of lead in drinking water is $50 \ ppb$.

Methemoglobinemia is caused by the presence of $X$ in drinking water. $X$ is

Cataract and skin cancer are caused by

Match the items in Column-$I$ with the compounds in Column-$II$.

Column-$I$	Column-$II$
$(A)$ Acid rain	$(1)$ $CHCl_2-CHF_2$
$(B)$ Photochemical smog	$(2)$ $CO$
$(C)$ Combination with hemoglobin	$(3)$ $CO_2$
$(D)$ Depletion of ozone layer	$(4)$ $SO_2$
	$(5)$ Unsaturated hydrocarbons

Consider the following.
Assertion $(A)$: $CO$ is poisonous to living beings.
Reason $(R)$: $CO$ binds to haemoglobin forming carboxyhaemoglobin,which is less stable than oxygen-haemoglobin complex.
Correct answer is