Environment Science /wbcs, psc, ssc exam – rlearn.in


1.The Environment Protection Act enacted on-

A. 1980

B. 1978

C. 1986

D. 1991

Answer: Option C

Explanation:The Environmental Protection Act enacted in 1986 with the objective of protection and improvement to the environment. The Act empowers the central government of India, to protect and improve the environment to the whole of India.

2.Ozone layer is being depleted by;

A. Smog.

B. Sulphur dioxide.

C. Carbon monoxide.

D. Chloroflurocarbon.(CFC)

Answer: Option D

Explanation : ozone depletion, gradually thinning of Earth’s ozone layer in the upper atmosphere caused by the release of chemical compounds containing gaseous chlorine or bromine from industry and other human activities. The thinning is most pronounced in the polar regions, especially over Antarctica. Ozone depletion is a major environmental problem because it increases the amount of ultraviolet (UV) radiation that reaches Earth’s surface, which increases the rate of skin cancer, eye cataracts, and genetic and immune system damage. The Montreal Protocol, ratified in 1987, was the first of several comprehensive international agreements enacted to halt the production and use of ozone-depleting chemicals. As a result of continued international cooperation on this issue, the ozone layer is expected to recover over time.

3.Ozone layer exists in;

A. Troposphere.

B. Stratosphere.

C. Mesosphere.

D. Ionosphere.

Answer: (Option B) 

Explanation :The ozone layer is the common term for the high concentration of ozone that is found in the stratosphere around 15–30km above the earth’s surface. It covers the entire planet and protects life on earth by absorbing harmful ultraviolet-B (UV-B) radiation from the sun.

4.World environment day is celebrated every year on-

A. Aug 12.

B. June 5.

C. September 8.

D. July 10.

Answer: Option (B) 

Explanation :

The United Nations designated June 5 to be observed as World Environment Day after a call for saving the environment from possible damage due to industrialization drew attention.The first World Environment Day was observed in 1974, giving a global platform for inspiring positive change in the environment.

5.Supersonic planes cause;

A. Noise pollution.

B. Air pollution.

C. Radioactive pollution.

D. Soil pollution.

Ans:( A)

Explanation :

These supersonic jets cause more pollution than the others and release some of the gases which result in the thinning of the ozone layer. As the ozone layer protects everyone by blocking the incoming UV rays.

6.Which of the following is a radioactive element

A. Uranium.

B. Argon.

C. Chromium.

D. Cobalt.


Explanation :

Uranium (chemical symbol U) is a naturally occurring radioactive element. When refined, uranium is a silvery-white metal. Uranium has three primary naturally occurring isotopes. For example, uranium has thirty-seven different isotopes, including uranium-235 and uranium-238.: U-238, U-235 and U-234.

7.Taj Mahal is threatened due to;

A. Sulphur dioxide.

B. Carbon dioxide.

C. Carbon monoxide.

D. Water vapour.

Answer :A

Explanation :

The Taj Mahal is built with white marble and is threatened by environmental pollution, especially due to sulphur dioxide. Sulphur dioxide is produced during combustion of fossil fuels, refining of petroleum and smelting of sulphur containing ores.

8.Which of the following process unit is used for air pollution control in chemical plants?

A. Thermal Oxidizer


C. Fluidized bed Combustion

D. None of these.

Answer: Option A 

Explanation : Thermal Oxidizer used in many chemical plants to control air pollution.It helps to destroy hazardous air pollutants and volatile organic compounds at a high temperature and releases them into the atmosphere.

9.Full form of CTBT is;

A. Comprehensive Nuclear-Test-Ban Treaty.

B. Comprehensive Test Bank Trust.

C. Comprehensive Trust Ban Treaty.

D. Comprehensive Test Ban Trusty.

Answer: Option A

Explanation :Comprehensive Nuclear-Test-Ban Treaty or CTBT bans nuclear explosive testing for everyone, everywhere, in all environments. CTBT makes very difficult for the countries to test or develop any nuclear weapon. The CTBT was opened for signature in 1996.

10.What is the full form of BOD?

A. Bactorial Oxygen Demand.

B. Biological Oxygen Demand.

C. Biological Oxide Demand.

D. None of these.

Answer: Option B

Explanation :BOD or Biological Oxygen Demand indicates the amount of dissolved oxygen needed by biological microorganisms in the biological process of breaking down organic substances in water.It is also called as Biochemical oxygen demand.

11.How much percentage of nitrogen consist in Earth’s Atmosphere?

A. 25%.

B. 12%.

C. 92%.

D. 78%.

Answer: Option D

Explanation : Earth atmosphere consists of a layer of gases. It is known as air. The composition of Dry air contains; 78.09% of Nitrogen(N2), 20.95% of Oxygen (O2), 0.93% of Argon (Ar) and 0.04% of Carbon dioxide(CO2).Also, it contains small amounts of other gases like; helium, neon, krypton, hydrogen and water vapour.

12.Full form of COD is;

A. Chemical Oxide Demand.

B. Chemical Oxygen Demand.

C. Chemical Ozone Demand.

D. None of these.

Answer: Option B

Explanation :COD is often used as a measurement of pollutants in water, wastewater, and aqueous hazardous wastes. One application of the COD test is to measure soluble COD in wastewater, since characterization of total COD in wastewater is critical for accurate modeling of biotransformation in wastewater treatment processes.

Another application is to rapidly infer biodegradability of samples from the COD tests. This is commonly accomplished by establishing a correlation between COD and BOD. This method has been found successful when the proportions and types of materials in a wastewater remain relatively constant. 

13.The disease “Itai Itai” is caused by;

A. Manganize.

B. Carbon.

C. Cadmium.

D. None of these.

Answer: Option C

Explanation :Itai-itai disease is caused by cadmium exposure produced as a result of human activities related to industrialisation, and this condition was first recognised in Japan in the 1960s.  Itai-itai disease is characterised by osteomalaecia with severe bone pain and is associated with renal tubular dysfunction.

14.Human being can hear range of sound frequency between;

A. 20-20,000 Hertz.

B. 10-1,000 Hertz.

C. 1-100 Hertz.

D. 1-7 Hertz

Answer: Option A

Explanation : 20-20,000 Hertz is the common human hearing range. Though it differs between individuals.

There are many animals that can hear beyond the range of human beings. For example, some whales can hear infrasonic sounds of 7 Hz in water, and, some bats and dolphins can hear frequencies up to 100,000 Hz.

The researcher has also found that human being can hear up to 200,000 Hz in underwater, which is 10 times higher than the top frequency(20,000 Hz) of a human can hear on land.

15.What percentage of land area should remain covered by forest in India to maintain ecological balance?

A. 10%

B. 5%

C. 33%

D. None of these.

Answer: Option C

Explanation :In the past, the British have introduced many scientific approaches for the development and management of the forest. But the first approach by the government was traced to National Forest Policy, 1894, which was revised in 1952. The policy focuses on the extension of forest and start a green movement in the country.

This policy states that 33% of the geographical area should be covered by forest/tree.Also, 60% of the land area will be in the hills and 20% will be in the plains.

Later the National Forest Policy again revised by the policymakers in 1988 and they give priority to the sustainable development of the forest.

  1. First International Conference on environment held on;

A. March,1968.

B. March,1970.

C. June,1970.

D. June,1972.

Answer: Option D

Explanation :United Nations Conference on the Human Environment, (also known as Stockholm Conference held in Stockholm, Sweden from June 5-16 in 1972.It was the first UN(United Nations) conference that focuses on international environmental issues.

17.With respect to environment science, full form of SPM is;

A. Suspended Partial Matter.

B. Suspended Particulate Matter.

C. Suspended Pollutant Matter.

D. None of these.

Answer: Option B

Explanation :Suspended particulate matter (SPM) are microscopic solids or liquids that contain organic and inorganic particles like; dust, pollen, smoke or liquid droplets. These particles may be dispersed through the air from combustion processes, industrial activities or natural sources.

18.In an ecosystem, bacteria are the

A. Producers.

B. Primary consumers.

C. Secondary consumers.

D. Decomposers.

Answer: Option D

Explanation :Decomposers are organisms that break down dead plants & animals and also break down waste of other organisms. Some of the common decomposers are bacteria, worms, slugs, snails, and fungi.

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