The water having more dissolved $\mathrm{O}_{2}$ is:

(D) water at $4^{\circ} \mathrm{C}$

(A) Water at $80^{\circ} \mathrm{C}$

JEE Main · 2021 · 22 Jul 2021 · Shift 2 · Environmental Chemistry

The water having more dissolved

O_{2}

is:

(A)Water at $8 0^{\circ} C$
(B)boiling water
(C)polluted water
(D)water at $4^{\circ} C$ ✓ Correct

Answer: (D)

Solution

Dissolution of a gas in water is exothermic, so raising the temperature shifts the equilibrium away from the dissolved state and the solubility of oxygen falls; Henry's constant for oxygen rises with temperature. Boiling drives the dissolved gas out altogether, and polluted water loses its oxygen to the aerobic decay of organic matter. Among the samples the coldest one retains the most gas, so the water having more dissolved oxygen is water at

4^{\circ} C

JEE Main · 2021 · 22 Jul 2021 · Shift 2 · Single correct option

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