Dear student,
Taj Mahal can be protected from acid rain by preventing the formation of acid rain. Acid rain formation can be prevented by preventing air pollution. Air pollution from automobiles, industries, burning fossil fuels etc can cause the formation of Nitrogen oxides and sulphur dioxide which mixes with rain water to lower the pH of rain water to 4. This acid rain when falls on the Taj Mahal erodes marble of Taj Mahal.
Air pollution can be prevented by using CNG fitted automobiles and using filters in exhaust. Filter must be placed in chimneys of industries to prevent the exhaust.
Regards