The phenomenon of marble cancer is due to :

Question

Accepted Answer

Marble cancer is a term used to describe the deterioration of marble structures, such as buildings and statues, primarily due to chemical reactions with acidic substances. The correct answer to the question is Option 2: Acid rain.

1. **Explanation for Option 2 (Acid rain):**
   Acid rain is a significant environmental problem that occurs when sulfur dioxide (SO2) and nitrogen oxides (NOx) are released into the atmosphere, often from industrial processes and vehicle emissions. These gases react with water vapor in the atmosphere to form sulfuric acid and nitric acid, which then fall to the ground as acid rain. When acid rain comes into contact with marble, which is primarily composed of calcium carbonate (CaCO3), a chemical reaction occurs. The acids in the rain react with the calcium carbonate, leading to the formation of calcium sulfate, carbon dioxide, and water. This reaction causes the marble to erode and deteriorate over time, a process commonly referred to as marble cancer. Therefore, acid rain is the primary cause of marble cancer, making Option 2 the correct answer.

2. **Explanation for why other options are incorrect:**

- **Option 1 (Soot particles):** Soot particles are tiny carbon particles that result from incomplete combustion of fossil fuels. While soot can cause discoloration and surface damage to buildings, it does not chemically react with marble in the same way that acid rain does. Soot primarily affects the appearance of marble rather than causing the chemical erosion associated with marble cancer.

- **Option 3 (CFCs):** Chlorofluorocarbons (CFCs) are compounds that were commonly used in refrigeration, air conditioning, and aerosol propellants. CFCs are known for their role in ozone layer depletion, but they do not directly affect marble structures. CFCs do not cause the chemical reactions necessary to produce marble cancer, making this option incorrect.

- **Option 4 (Fog):** Fog is a weather phenomenon consisting of tiny water droplets suspended in the air. While fog can contribute to moisture accumulation on surfaces, it does not contain the acidic components necessary to cause marble cancer. Fog alone does not lead to the chemical erosion of marble, so it is not responsible for marble cancer.

In conclusion, acid rain is the primary cause of marble cancer due to its ability to chemically react with marble and cause deterioration, making Option 2 the correct answer.