Which gaseous pollutant,even in low concentrations,causes respiratory distress such as inflammation and irritation in the human respiratory tract?

The concentration of fluoride,lead,nitrate and iron in a water sample from an underground lake was found to be $1000 \ ppb, 40 \ ppb, 100 \ ppm$ and $0.2 \ ppm,$ respectively. This water is unsuitable for drinking due to high concentration of:

Match the following items correctly:

List-$I$	List-$II$
$(1)$ Vegetable waste	$(A)$ Takes $3$ to $5$ months for natural decomposition
$(2)$ Plastic materials	$(B)$ Takes $7$ to $10$ months for natural decomposition
$(3)$ Agricultural waste	$(C)$ Remains in original form for decades without decomposition

Given below are two statements:
Statement $I:$ Classical smog occurs in cool humid climate. It is a reducing mixture of smoke,fog and sulphur dioxide.
Statement $II:$ Photochemical smog has components,ozone,nitric oxide,acrolein,formaldehyde,$PAN$ etc.
In the light of above statements,choose the most appropriate answer from the options given below:

What efforts are being made by the government to save the Taj Mahal?

The maximum prescribed concentration of copper in drinking water is ........ $ppm$.