Which of the following industries is the best source of increasing $CO$ levels in the atmosphere?

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

Which oxide of nitrogen is not a common pollutant introduced into the atmosphere both due to natural and human activity?

Identify $X$,$Y$,and $Z$ in the following reaction. (Equation not balanced)
$ClO + NO_2$ $\rightarrow \underline{X}$ $\xrightarrow{H_2O} \underline{Y} + \underline{Z}$

Which of the following air pollutants is likely $NOT$ to produce photochemical smog?

The metal ion responsible for the Minamata disease is