Which of the following is a particulate pollutant?

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	$(III)$ $50 \text{ ppb}$

How is the troposphere damaged by oxides of carbon?

Write down the reactions involved during the formation of photochemical smog.

Which one of the following statements is not correct?

Which of the given statements are correct, when carboxyhaemoglobin reaches $3-4 \%$ in blood?
$(I)$ Leads to headache
$(II)$ Results in cardiovascular problems
$(III)$ Increases the body temperature
$(IV)$ Leads to diarrhoea