Taj Mahal is threatened by which atmospheric pollutant released by Mathura refinery?
A.\[S{O_2}\]
B.\[C{O_2}\]
C.\[CO\]
D.\[C{l_2}\]

Hint:Identify the chemical composition of the material of which Taj Mahal is made up of. Then see which of the given options can be harmful to that material. Emission of certain oxides in the atmosphere by factories causes acid rain.

Complete answer:
Taj Mahal is mainly made up of marble. So let us see what the main reason for degradation of marble is. Marble is chemically calcium carbonate $(CaC{O_3})$ . Now the factories near the Taj Mahal region produce mainly sulfur oxides and nitrogen oxides. Also the direction of wind which is towards Taj Mahal contributes to the degradation of its marble.
Also the main cause why these factories are set up near Taj Mahal is the Yamuna River which flows alongside Taj Mahal. Now these factories mainly the Mathura refinery emits sulfur and nitrogen oxides. These oxides with the flow of air leads to acid rain in the Taj Mahal region. This poisonous acid rain causes the degradation of Taj Mahal’s marble which is basically calcium carbonate.
The sulfur oxides and nitrogen oxides get converted into sulfuric acid and nitric acid respectively which causes acid rain.
The reaction of degradation of calcium carbonate by sulfuric acid is given below,
${H_2}S{O_4} + CaC{O_3} \to CaS{O_4} + {H_2}O + C{O_2}$
The reaction of degradation of calcium carbonate by nitric acid is given below,
$HN{O_3} + CaC{O_3} \to Ca{(N{O_3})_2} + {H_2}O + C{O_2}$
These reactions show that calcium carbonate is degraded to calcium sulphate and calcium nitrate which cause corrosion and slow erosion of the marble’s surface. This results in a yellowish marble surface.
We have seen sulfur oxide and nitrogen oxide are the main constituent of acid rain and we have sulfur oxide in the option.

So, option A is the correct answer.
Note:
Though acid rain has its unique name but it smells and tastes no different than the normal rain. It can neither rot human skin. But it can cause serious diseases like asthma, cancer, heart diseases.