Science & Biotechnology

Total Questions: 50

31. Which of the following is a cause of pollution of water resources? [S.S.C. JE Mechanical Exam 22.03.2021 (Shift-I)]

(a) Dead aquatic animals
(b) Dead aquatic plants
(c) Radioactive substances
(d) Deforestation

Correct Answer: (c) Radioactive substances

Solution:Radioactive substances are the cause of pollution of water resources. The substances which keep on generating energy on their own are called radioactive substances. Their radiation is in the form of alpha, beta, gamma, and electron. This type of radiation from nuclear waste is extremely harmful to organisms, as it causes mutations at a very high rate. Radiosensitivity was discovered by the French scientist Henri Becquerel. Pollution is caused by human activities such as nuclear power plants, nuclear weapons testing, and the construction and use of radioactive sources. The Government of India passed the Prevention and Control of Water Pollution Act in the year 1974 to save our water resources from getting polluted.

32. The least preferred technique in the disposal of Municipal Solid Waste is— [S.S.C. Online Graduate Level (T-I) 29.08.2016 (Shift-II)]

(a) Incineration
(b) Composting
(c) Land filling
(d) Briquetting

Correct Answer: (d) Briquetting

Solution:Waste management varies from region to region for a number of reasons, including the type of waste material, the use of the surrounding land, and the area available. Techniques like incineration, composting, landfilling, etc. are generally used by the municipality, but the briquetting technique is the least preferred.

33. During which of the following operating conditions of an automobile, carbon monoxide content in exhaust gas is maximum? [S.S.C. Online Graduate Level (T-I) 2.09.2016 (Shift-I)]

(a) Acceleration
(b) Cruising
(c) Idle running
(d) Deacceleration

Correct Answer: (c) Idle running

Solution:The carbon monoxide content in the exhaust gas is maximum under Idle running conditions.

34. Which of the following greenhouse gases has the greatest heat-trapping ability? [S.S.C. Online Graduate Level (T-I) 8.09.2016 (Shift-III)]

(a) Chlorofluorocarbon
(b) Methane
(c) Carbon dioxide
(d) Nitrous oxide

Correct Answer: (a) Chlorofluorocarbon

Solution:The greatest heat-trapping ability among the above options is that of chlorofluorocarbons.

35. The depletion of ozone in the atmosphere has been linked to ___. [S.S.C. Online Constable GD 19.02.2019 (Shift-I)]

(a) phenol - formaldehyde
(b) polyvinyl chloride
(c) Chlorofluorocarbons
(d) Polytetrafluoroethylene

Correct Answer: (c) Chlorofluorocarbons

Solution:Chlorofluorocarbons (CFCs) are mostly used as refrigerants and destroy the protective layer of ozone (O₃) located in the Earth’s atmosphere. Ozone protects Earth from harmful ultraviolet (UV-B) rays produced by the Sun. CFCs and HCFCs also heat the Earth's lower atmosphere, causing changes in the global climate.

36. Incomplete combustion of fuels like petrol and diesel produces— [S.S.C. Online CHSL (T-I) 15.03.2018 (Shift-II)]

(a) carbon dioxide
(b) carbon monoxide
(c) nitric oxide
(d) nitrogen dioxide

Correct Answer: (b) carbon monoxide

Solution:Fuels like petrol, diesel, and coal in the presence of less oxygen, i.e., their incomplete combustion, produce carbon monoxide gas. Carbon (C) is found in these fuels. Carbon is left behind by incomplete combustion, which then produces CO (carbon monoxide). This is a toxic gas.

37. Automobile emissions promote toxic pollutants called— [S.S.C. Online CHSL (T-I) 11.01.2017 (Shift-I)]

(a) carbon dioxide
(b) Sulfur dioxide
(c) carbon monoxide
(d) nitrous oxide

Correct Answer: (c) carbon monoxide

Solution:Carbon monoxide is a colorless gas. This gas is slightly lighter in the air. Its molecular formula is CO. When its excessive amount enters the body, suffocation occurs, after which unconsciousness comes and leads to death. It is found in the smoke from automobile vehicles.

38. Which of the following gases is produced due to incomplete combustion of fuel? [S.S.C. Online CHSL (T-I) 18.01.2017 (Shift-II)]

(a) Carbon Dioxide
(b) Carbon Monoxide
(c) Methane
(d) Ethane

Correct Answer: (b) Carbon Monoxide

Solution:

Incomplete combustion of a fuel produces carbon monoxide (CO) gas. Combustion of fuel in the presence of less oxygen is considered incomplete combustion because due to lack of oxygen, all the oxygen rapidly reacts with the fuel and turns into CO₂ gas. Therefore, the carbon (C) of the remaining fuel reacts with the CO₂ present in the atmosphere to form carbon monoxide (CO).

39. Which of the following gases emitted from automobile exhaust is poisonous? [S.S.C. Online CHSL (T-I) 16.01.2017 (Shift-I)]

(a) Carbon monoxide
(b) Carbon dioxide
(c) Hydrocarbons
(d) Sulphur dioxide

Correct Answer: (a) Carbon monoxide

Solution:Carbon monoxide (CO) is a toxic gas. It is often found in the smoke of motor vehicles, which run on petrol, diesel, or gasoline fuels.

40. Which of the following three R’s are regarded as environment friendly? [S.S.C. Online Graduate Level (T-I) 11.08.2017 (Shift-II)]

(a) reduce, reuse, recycle
(b) reduce - reuse, recycle
(c) recollect, reuse, reuse
(d) reduce, renew, reuse

Correct Answer: (a) reduce, reuse, recycle

Solution:The three R’s that are regarded as environment friendly are “reduce - reuse - recycle”.

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