classical smog

acid rain

photochemical smog

organic waste

$$Cl\mathop O\limits^ \bullet \left( g \right) + O\left( g \right) \to \mathop C\limits^ \bullet l\left( g \right) + {O_2}(g)$$

$$C{F_2}C{l_2}\left( g \right)\,\buildrel {uv} \over \longrightarrow \mathop {\,C}\limits^ \bullet l\left( g \right) + \mathop C\limits^ \bullet {F_2}Cl\left( g \right)$$

$$C{H_4} + 2{O_3}\, \to \,3C{H_2} = O + 3{H_2}O$$

$$HOCl\left( g \right)\,\buildrel {hv} \over \longrightarrow \,\mathop O\limits^ \bullet H\left( g \right) + \mathop C\limits^ \bullet l\left( g \right)$$

B is more polluted than A.

A is suitable for drinking, whereas B is not .

Both A and B are suitable for dirnking

A is more polluted than B.

> 50 ppm of lead

> 50 ppm of chloride

> 50 ppm of nitrate

> 100 ppm of sulphate