Practice MCQ Questions and answers on Chemistry-GK

DDT appeared to be with a significant potential for accumulation through food chains.

Higher concentration of nitrogen dioxide in atmosphere air causes bronchitis.

Polycyclic aromatic hydrocarbons (PAHs) are formed during incomplete combustion. Domestic wood burning and road traffic are the major sources of PAHs. Exposure to PAH-containing substances increases the risk of cancer in humans. The carcinogenicity of PAHs is associated with the complexity of the molecule, i.e., increasing number of benzenoid rings, and with metabolic activation to reactive diol epoxide intermediates and their subsequent covalent binding to critical targets in DNA. Quantitative cancer risk estimates of PAHs as air pollutants are very uncertain because of the lack of useful, good-quality data.

Asbestosis, also called white lung, lung disease that is caused by the prolonged inhalation of asbestos fibres.

Automobile exhaust is a man-made source of air pollution.

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.

Most commercial flights are confined to the troposphere, but high-level supersonic aircraft inject pollutants into the stratosphere, which leads to the thinning of the ozone layer. Of these nitrogen oxides are especially harmful.

Ozone depletion occurs when chlorofluorocarbons (CFCs) and halons—gases formerly found in aerosol spray cans and refrigerants—are released into the atmosphere.

A flue-gas stack is a type of chimney, a vertical pipe, channel or similar structure through which combustion product gases called flue gases are exhausted to the outside air. Flue gases are produced when coal, oil, natural gas, wood or any other fuel is combusted in an industrial furnace, a power plant’s steam-generating boiler, or other large combustion device. Flue gas is usually composed of carbon dioxide (CO2) and water vapor as well as nitrogen and excess oxygen remaining from the intake combustion air. It also contains a small percentage of pollutants such as particulate matter, carbon monoxide, nitrogen oxides and sulfur oxides. The flue gas stacks are often quite tall, up to 400 metres (1300 feet) or more, so as to disperse the exhaust pollutants over a greater area and thereby reduce the concentration of the pollutants to the levels required by governmental environmental policy and environmental regulation.

Acid rain results when sulphur dioxide (SO2) and nitrogen oxides (NOX) are emitted into the atmosphere and transported by wind and air currents.