Given below are two statements, one is labelled as Assertion A and the other…
2020
Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Polluted rivers with very high values of Biological Oxygen Demand (BOD) may produce a foul smell. Reason R: Anaerobic bacteria produce sulphur dioxide and oxides of nitrogen. In light of the above statements, choose the most appropriate answer from the options given below.
- A.
Both A and R are correct and R is the correct explanation of A
- B.
Both A and R are correct but R is NOT the correct explanation of A
- C.
A is correct but R is not correct
- D.
A is not correct but R is correct
Attempted by 2 students.
Show answer & explanation
Correct answer: C
The correct answer is: A is correct but R is not correct.
Biological Oxygen Demand (BOD) measures the amount of dissolved oxygen required by microorganisms to decompose organic matter in water. A very high BOD value indicates heavy organic pollution and rapid consumption of dissolved oxygen. When dissolved oxygen becomes very low, anaerobic decomposition begins and foul-smelling gases may be produced. Therefore, Assertion A is correct.
Reason R is not correct because anaerobic bacteria commonly produce gases such as hydrogen sulphide and methane under such conditions. They do not produce sulphur dioxide and oxides of nitrogen as stated in the reason.