The compound that is $NOT$ a common component of photochemical smog is

Pollution is a change in physical,chemical or biological characters of our land and water that may be

Match the pollutant in List-$I$ with its maximum permissible limit in drinking water given in List-$II$.

List-$I$	List-$II$
$(A)$ Lead	$(I)$ $500 \text{ ppm}$
$(B)$ Sulphate	$(II)$ $50 \text{ ppm}$
$(C)$ Nitrate	$(III)$ $50 \text{ ppb}$

The relative contribution of $O_3$,$N_2O$,and $H_2O$ to global warming is in the ratio of ......

Photochemical smog is formed by .....

$A$ factory was started near a village. Soon,the villagers began experiencing the presence of undesirable gases in the atmosphere,leading to symptoms like headaches,chest pain,colds,dry throats,and breathing difficulties. The villagers blamed the smoke emitted from the factory chimney for these problems. Describe what might have happened and provide the chemical equations to support your explanation.