Environmental Chemistry — Page 10 | JEE Chemistry

JEE Chemistry · 92 questions · Page 10 of 10 · Click an option or "Show Solution" to reveal answer

Q91

Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R. Assertion A : Polluted water may have a value of BOD of the order of 17 ppm. Reason R : BOD is a measure of oxygen required to oxidise both the bio-degradable an non-biodegradable organic material in water. In the 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.

Correct Answer

Option C

Solution

Highly polluted water could have a BOD value of 17 ppm or more.

The amount of oxygen required by bacteria to break down the organic matter present in a certain volume of a sample of water is called Biochemical Oxygen demand (BOD).

Hence A is correct but R is not correct.

Q92

The measured BOD values for four different water samples (A-D) are as follows: A = 3 ppm; B = 18 ppm; C = 21 ppm; D = 4 ppm. The water samples which can be called as highly polluted with organic wastes, are :

A A and B

B A and D

C B and C

D B and D

Correct Answer

Option C

Solution

Highly polluted water should have BOD value of 17 ppm or more