Question

Which of the following causes acid rain?
A. Oxides of sulfur and carbon dioxide
B. Oxides of nitrogen and carbon monoxide
C. Hydrogen sulfide and carbon dioxide
D. Oxides of sulfur and nitrogen

Answer 1

Hint: As we know that $pH$ is used to measure the strength of acids and bases. Acids have $pH$ values less than that of water. Similarly, acid rain also has less $pH$ value than that in water. Using $pH$ value, we can determine whether the solution is acidic or basic.

Complete step by step answer:
Pollution is caused by harmful pollutants. Pollution is of different types-air, water, soil pollution etc. When we burn fossil fuels or smoke produced from factories or thermal power plants, it leads to air pollution.
When hydrocarbons are undergoing combustion, we get carbon monoxide, nitrogen oxide and carbon dioxide as by products. The products formed are gases which when mixed with air leads to air pollution. There is a presence of water vapor in the atmosphere which when mixed with the sulfur dioxide and nitrogen oxides, it gives sulfuric acid or nitric acid. This is precipitated as acid rain. Acid rain mainly consists of sulfuric acid and nitric acid. When sulfur dioxide reacts with water, it gives sulfurous acid as given below:
$S{O}_2+H_{2}O\to H_{2}S{O}_3$
This sulfurous acid reacts with oxygen which gives sulfuric acid.
i.e. $H_{2}S{O}_3+O_2\to H_{2}S{O}_4$
Similarly nitrogen dioxide reacts with water to give nitric acid and nitrous acid. Nitric acid reacts with oxygen forming nitric acid.
$N{O}_2+H_{2}O\to HN{O}_3+HN{O}_2$
$HN{O}_2+O_2\to HN{O}_3$
Thus acid rain is caused by oxides of sulfur and oxides of nitrogen.

So, the correct answer is Option D.

Note: Major ways to control acid rain are:
Alternate fuels.
Reduce energy consumption.
Usage of alternate mode of transportation.
Removal of oxides of sulfur and nitrogen before releasing flue gas desulfurization.
Usage of renewable energy.