Excess nitrate in drinking water can cause

Which one of the following is not a common component of photo-chemical smog?

What steps should be taken to reduce the production of acid rain?

Given below are two statements :
Statement $I:$ The nutrient deficient water bodies lead to eutrophication.
Statement $II:$ Eutrophication leads to decrease in the level of oxygen in the water bodies.
In the light of the above statements,choose the correct answer from the options given below:

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 $50 \ ppb$.

On the surface of polar stratospheric clouds,hydrolysis of chlorine nitrate $(ClONO_2)$ gives $A$ and $B$,while its reaction with $HCl$ produces $B$ and $C$. $A, B$ and $C$ are,respectively: