Oxide of sulphur present in the atmosphere are washed down by rains to cause :

Solution (By Examveda Team)

Option A: Depletion of fossil fuel reserves
Oxides of sulfur in the atmosphere do not directly cause the depletion of fossil fuel reserves.
Fossil fuel depletion is due to the consumption of natural resources rather than chemical reactions involving atmospheric sulfur oxides.

Option B: Eutrophication in lakes
Eutrophication in lakes is typically caused by an excess of nutrients like nitrogen and phosphorus rather than sulfur oxides.
While sulfur oxides can contribute to water pollution, they are not the primary cause of eutrophication.

Option C: Lowering of pH of soil
Oxides of sulfur, such as sulfur dioxide (SO₂) and sulfur trioxide (SO₃), can react with water in the atmosphere to form sulfuric acid (H₂SO₄).
When these acidic compounds are washed down by rain, they cause acid rain, which lowers the pH of soil.
This acidification of soil can harm plant life and alter soil chemistry, making it the correct answer.

Option D: Industrial smog formation
While sulfur oxides can contribute to air pollution and visibility issues, industrial smog is primarily formed by particulate matter and other pollutants such as nitrogen oxides.
Sulfur oxides may contribute to smog, but they are not the main cause of industrial smog formation.

Conclusion:
The correct answer is Option C: Lowering of pH of soil.
Sulfur oxides present in the atmosphere lead to acid rain, which lowers the soil pH, impacting soil health and plant growth.