The concentration of dissolved Oxygen in water for growth of fish should be more than $\underline{\mathrm{X}}$ ppm and Biochemical Oxygen Demand in clean water should be less than $\underline{Y}$ ppm. $X$ and $Y$ in ppm are, respectively.

JEE Main · 2023 · 29 Jan 2023 · Shift 2 · Environmental Chemistry

The concentration of dissolved Oxygen in water for growth of fish should be more than

\underline{X}

ppm and Biochemical Oxygen Demand in clean water should be less than

\underline{Y}

ppm.

X

and

Y

in ppm are, respectively.

(A)X: 6, Y: 5✓ Correct
(B)X: 5, Y: 6
(C)X: 4, Y: 15
(D)X: 6, Y: 12

Answer: (A)

Solution

For fish to survive and grow, the oxygen dissolved in the water must stay above about

6

ppm, below which aquatic life is endangered. Clean, unpolluted water contains little biodegradable organic matter and so has a low biochemical oxygen demand, below about

5

ppm, whereas polluted water shows much higher values. The required figures are a dissolved oxygen greater than

6

ppm and a biochemical oxygen demand less than

5

ppm.

JEE Main · 2023 · 29 Jan 2023 · Shift 2 · Single correct option

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