Pollution (Part-II)

Total Questions: 50

21. Biological Oxygen Demand (BOD) is an indication of pollution in: [Uttarakhand U.D.A./L.D.A. (Mains) 2007]

(a) Aquatic environment
(b) Soil
(c) Air
(d) All the above

Correct Answer: (a) Aquatic environment

Solution:Biological oxygen demand is the amount of dissolved oxygen needed by an anaerobic biological organism to break down organic material present in a given water sample at a certain temperature over a specific period. Increase in BOD shows a high level of organic pollution of water since all organic and inorganic waste use dissolved oxygen for decomposition. This means if there is less pollution, the dissolved oxygen will be high and vice versa. Thus BOD works as an indicator of pollution in the aquatic environment.

22. A water body having high B.O.D. indicates that its water is- [U.P.P.C.S. (Pre) 2007]

(a) Receiving minerals
(b) Being aerated
(c) Being contaminated by sewage
(d) Atrophic

Correct Answer: (c) Being contaminated by sewage

Solution:BOD indicates the amount of organic matter present in water. Therefore, a low BOD is an indicator of good quality water, while a high BOD indicates polluted water.

23. The water pollution in a river is determined by measuring the dissolved amount of: [U.P.P.C.S. (Pre) 2011]

(a) Chlorine
(b) Nitrogen
(c) Ozone
(d) Oxygen

Correct Answer: (d) Oxygen

Solution:BOD indicates the amount of organic matter present in water. Therefore, a low BOD is an indicator of good quality water, while a high BOD indicates polluted water.

24. Water pollution of river is measured by- [U.P.R.O./.A.R.O. (Pre) 2021]

(a) Amount of Chlorine dissolved in water.
(b) Amount of Ozone dissolved in water.
(c) Amount of Nitrogen dissolved in water.
(d) Amount of Oxygen dissolved in water.

Correct Answer: (d) Amount of Oxygen dissolved in water.

Solution:Biochemical Oxygen Demand (BOD, also called biological oxygen demand) is the amount of Dissolved Oxygen (DO) needed (i.e., demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. The BOD value is most commonly expressed in milligrams of oxygen consumed per litre of sample during 5 days of incubation at 20°C and is often used as a surrogate of the degree of organic pollution of water. BOD can be used as a gauge of the effectiveness of wastewater treatment plants.

25. Biological Oxygen Demand (BOD) is a standard criterion for: [I.A.S. (Pre) 2017, U.P.P.C.S. (Pre) 2023]

(a) Measuring oxygen levels in blood.
(b) Computing oxygen levels in forest ecosystems.
(c) Pollution assay in aquatic ecosystems.
(d) Assessing oxygen levels in high altitude regions.

Correct Answer: (c) Pollution assay in aquatic ecosystems.

Solution:BOD is a standard criterion for pollution assay in aquatic ecosystems.

26. BOD is maximum in the Ganga river between: [U.P.P.C.S. (Spl) (Mains) 2008]

(a) Haridwar and Kanpur
(b) Kanpur and Allahabad
(c) Allahabad and Patna
(d) Patna and Uluberia

Correct Answer: (b) Kanpur and Allahabad

Solution:BOD is maximum in the Ganga river between Kanpur and Allahabad as Kanpur discharge heavy amount of pollutants in Ganga. As a result of which BOD is high here.

27. Consider the following statements and choose the right options given below: [Chhattisgarh P.C.S. (Pre) 2023]

1. Presence of large amounts of nutrients in water also causes excessive growth of planktonic (free- floating) algae, called an algal bloom.

2. Algal bloom causes deterioration of water quality and fish mortality.

(a) Only the Statement (1) is correct.
(b) Only the statement (2) is correct.
(c) Both the statements (1) and (2) are in-correct.
(d) Both the Statements (1) and (2) are correct.

Correct Answer: (b) Only the statement (2) is correct.

Solution:Algal blooms are dense layers of tiny green plants that occur on the surface of lakes and other bodies of water when there is an overabudance of nutrients on which algae depends. Algal bloom causes deterioration of water quality and fish mortality. Harmful algal blooms, dead zones and fish kills are the result of a process called as eutrophication. So both the statements are correct.

28. The problem of water pollution with Arsenic is maximum in- [U.P.P.C.S. (Pre) (Re-Exam) 2015]

(a) Haryana
(b) Rajasthan
(c) Madhya Pradesh
(d) West Bengal

Correct Answer: (d) West Bengal

Solution:Groundwater in Brahmaputra, Gangetic plains of India and Padma Meghna plains of Bangladesh is highly polluted with arsenic. Groundwater in seven states of India- West Bengal, Jharkhand, Bihar, Uttar Pradesh, Assam, Manipur and Chhattisgarh is polluted with arsenic. The first instance of water pollution with arsenic came to notice in 1978. Notably, the permissible range of arsenic in groundwater is 10 Microgram per liter.

29. Which country has natural arsenic water contamination? [U.P.P.C.S. (Pre) 2022]

(a) Bangladesh
(b) Pakistan
(c) Sri Lanka
(d) Bhutan

Correct Answer: (a) Bangladesh

Solution:Arsenic contamination fo groundwater in Bangladesh has been recognized as a major public health problem. The arsenic contamination was first discovered in water from tubewells in 1993 in a northern district of Bangladesh. Fifty million people of Bangladesh were estimated to have been at risk of exposure to arsenic through consumption of water from contaminated tubewells.

30. Which of the following rivers is called 'biological desert' on account of its pollutants? [U.P.P.C.S. (Pre) 2012]

(a) Yamuna
(b) Periyar
(c) Damodar
(d) Mahanadi

Correct Answer: (c) Damodar

Solution:Damodar, considered as 'Sorrow of Bengal' due to its devastating floods, has now become the sorrow of both Jharkhand and Bengal owing to excessive pollution. The enormous quantity of pollutants coming out from the mines, industries, cities and agricultural fields have so much degraded the quality of river that it has virtually become a biological desert.

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