Explanation

Acid rain results from air pollution by oxides of nitrogen ($NO_{x}$) and sulpaur ($SO_{x}$). These gases react with water and form acids. $SO_{2}\ \ + \ \ H_{2}O\ \$ $\rightarrow H_{2}{SO}_{3}$ $SO_{3}\ \ + \ \ H_{2}O\ \$ $\rightarrow H_{2}SO_{4}$ $N_{2}O_{5} + H_{2}O$ $\rightarrow 2HNO_{3}$ When the pH of rain is below 5.6, it is called acid rain.