SSC Selection Post - Higher Secondary Level - 30th July 2025 - Shift 2

Correct Answer:-

Sulfur dioxide and nitrogen oxides

Explanation:-

Acid rain is primarily caused by the emission of sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) into the atmosphere. When these gases react with water vapor present in the air, they convert into sulfuric acid and nitric acid. Subsequently, these acids fall to the earth with rain, snow, or fog, which is known as acid rain.

The other options are incorrect because carbon monoxide and methane are greenhouse gases that contribute to global warming. Chlorofluorocarbons (CFCs) are primarily responsible for the depletion of the ozone layer. Lead and mercury compounds are toxic metal pollutants, but they are not the primary cause of acid rain.

Key Points

The largest source of acid rain is the burning of fossil fuels (coal and oil) from power plants and vehicles. This rain is extremely harmful to buildings (e.g., the yellowing of the Taj Mahal), soil fertility, and aquatic life. Acid rain lowers the pH level of water, increasing the acidity of lakes and rivers.

Important Questions and Answers

Question: What is the normal pH level of rain?

Answer: The pH of normal rain is approximately 5.6, whereas the pH of acid rain falls below this (often below 5.0).

Question: What is the effect of acid rain on historical monuments called?

Answer: Stone Cancer or the erosion of marble.