Question

Which of the following gases is causing acid rain?
A. Carbon monoxide and carbon dioxide
B. Sulphur dioxide and oxides of nitrogen
C. Oxides of nitrogen and carbon dioxide
D. None of these

Answer 1

Hint: Acid rain is precipitation that has pH of less than of natural rainwater. The pH is a measure of the concentration of hydrogen ions in water. It determines if a solution is acidic or basic.

Complete Answer:
- The presence of harmful pollutants in air leads to pollution. Human activities like burning of fossil fuels, smoke from factories, thermal power plants, etc., contribute to air pollution.
- The process of combustion mainly produces carbon monoxide, nitrogen oxide and carbon dioxide as a by-product. These gases mix with the air and contribute to air pollution. When sulphur dioxide and oxides of nitrogen present in the atmosphere mix water vapour, it forms sulphuric acid or nitric acid and precipitate as acid rain.

There are two main sources for it:
1. Natural Source - Chemicals released by rotting vegetation and volcanic eruptions can cause acid rain.
2. Human Sources- Human activities emit harmful gases through burning of fossil fuels, industrial factories, power-generating plants and vehicles etc. They are the major cause of acid rain.

Acid rain has several harmful effects as:
1. It increases the acidity of water bodies causing a threat to aquatic animals
2. It affects the food chain in turn
3. It also harms forest by damaging the leaves of trees and removing essential nutrients from the soil. It also makes it hard for trees to take up water.

So the right answer is option B, Sulphur dioxide and oxides of nitrogen.

Note: By designing cleaner power plants and using fewer fossil fuels, we can reduce the number of pollutants that create acid rain.