JEE Main · 2019 · 12 Jan 2019 · Shift 1 · Environmental Chemistry

Water sample with BOD vales of 4 ppm and 18 ppm respectively are

(A)Clean and clean
(B)Highly polluted and clean
(C)Clean and highly polluted✓ Correct
(D)Highly polluted and highly polluted.

Answer: (C)

Solution

BOD, the biochemical oxygen demand, measures how much oxygen micro-organisms need to break down the organic matter in water, so a high value signals heavy organic pollution. Clean water sits below about

5 ppm

, while badly polluted water runs to roughly

17 ppm

or more. A sample at

4 ppm

is therefore clean, and one at

18 ppm

is highly polluted.

JEE Main · 2019 · 12 Jan 2019 · Shift 1 · Single correct option

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