JEE Main levelSingle correct optionDifficulty 2 of 3ev128
Assertion (A): The COD of a sewage sample is generally greater than its BOD.
Reason (R): Dichromate in acid oxidises organic matter that bacteria do not oxidise in 5 days.
AA is false but R is true
BBoth A and R are true and R is the correct explanation of A
CBoth A and R are true but R is not the correct explanation of A
DA is true but R is false
Answer: B
Dichromate is a strong chemical oxidant and also oxidises organic matter that is not biodegradable, or is oxidised only slowly by bacteria. So COD is generally the larger value, and R explains A.