Free Man and His Environment MCQs with Answers

351. Ozone filters ultraviolet radiations from the sun in the upper:

• A. Biosphere
• B. Atmosphere
• C. Lithosphere
• D. Hydrosphere

Explanation: [A] Biosphere is made up of the parts of earth where life exists[B] Atmosphere is the layer of gases around earth and ozone is present in it to filter uv rays from sun[C] Lithosphere is the solid outer part of earth[D] hydrosphere; total amount of water on a planet

352. In aquatic ecosystem, human activities may accelerate the process of:

• A. Eutrophication
• B. Photosynthesis
• C. Decomposition
• D. Recycling

Explanation: Option A is correct since Eutrophication is the process in which the water body has an enriched amount of nutrients and thus more life and decaying bodies which cause smell. And this process is enhanced by human activities like use of washing powders and fertilizers.Option B is incorrect because Photosynthesis is the process by which plants prepare their food by using sunlight and this process cannot be accelerated by human activities.Option C is incorrect because Decomposition is process of decaying dead matter and done by bacteria human activities have no role.Option D is incorrect because Recycling is process by which old things are reused.

353. The natural heat energy trapped underground is:

• A. Geothermal energy
• B. Thermal energy
• C. Electric energy
• D. Solar energy

Explanation: Option A is correct since Geothermal energy is natural heat trapped underground.Option B is incorrect because Thermal energy is only heat energy.Option C is incorrect because Electric energy is due to potential difference between two points.Option D is incorrect because Solar energy is energy of sunlight.

354. Which one of the following is depleting and causing thinning of ozone?

• A. Chlorine
• B. Bromine
• C. Chlorofluorocarbon
• D. Carbon

Explanation: Thinning in the ozone layer is caused by increasing concentrations of ozone-depleting chemicals - chlorofluorocarbons or CFCs (compounds with chlorine and/or fluorine attached to carbon) and to a lesser extent halons (similar compounds with bromine or iodine).

355. Excessive enrichment of water with nutrients by human activity by which large amount of living organic matter grows is called:

• A. Archeotrophication
• B. Eutrophication
• C. Enrichment
• D. Low Trophication

Explanation: Eutrophication is characterized by excessive plant and algal growth due to the increased availability of one or more limiting growth factors needed for photosynthesis.

356. The cause of acid rain is

• A. Oxides of carbon
• B. Oxides of nitrogen and Sulphur
• C. Oxides of Sulphur
• D. Oxides of nitrogen

Explanation: Nitrogen dioxide acts as a catalyst and reacts with sulphur dioxide to form sulphur trioxide, which is the main culprit of acid rain.

357. As a result of destruction of ozone layer there is significant increase in:

• A. Ultra-violet radiations
• B. Greenhouse gases
• C. Nitrogen oxide
• D. Sulphur oxide

Explanation: The ozone layer absorbs Ultra-violet radiation. Depletion of ozone layer results in increased amount of Ultra-violet radiation reaching the Earth's surface.

358. Higher rate of a biological activity in a nutrient rich pond water is called:

• A. Water pollution
• B. Air pollution
• C. Eutrophication
• D. Industrial effects

Explanation: Eutrophication is characterized as the excess growth of algae or aquatic plants due to an increase in one or more growth limiting factors such as nutrients, sunlight, and carbon dioxide.

359. The decline in the thickness of the ozone layer is caused by:

• A. Increasing levels of nitrogen oxide
• B. Decreasing level of O2
• C. Decreasing level of CFCs
• D. Increasing levels of CFCs

Explanation: An increase in CFC gas is responsible for the deterioration of the ozone layer. 'When chlorofluorocarbons (CFC) drift upwards towards the stratosphere, they come in contact with the Ozone layer. This leads to a chemical reaction where the CFC molecules are broken up by ultraviolet radiation, releasing chlorine atoms, which are able to destroy ozone molecules.' (via. byjus.com)

360. Chemicals used for destroying agricultural competitors are known as:

• A. Antibiotics
• B. Pesticides
• C. Disinfectants
• D. Chemotherapeutic agents

Explanation: Pesticides are a class of chemicals that are used to kill crop-eating insects, unwanted weeds etc. Insecticides, herbicides, nematicides; they all come under the umbrella of pesticides.