JEE Main · 2026 · 22 Jan 2026 · Shift 1 · Solutions

Consider a solution of

CO_{2} (g)

dissolved in water in a closed container.

Which one of the following plots correctly represents variation of log (partial pressure of CO2 in vapour phase above water) [y-axis] with log (mole fraction of

CO_{2}

in water) [x-axis] at

2 5^{\circ} C

(A)(see structure)
(B)(see structure)
(C)(see structure)
✓ Correct
(D)(see structure)

Answer: (C)

Solution

By Henry's law the partial pressure of a gas above the solution is proportional to its mole fraction in the liquid,

p = K_{H} x

. Taking logarithms,

lo g p = lo g x + lo g K_{H}

, a straight line of unit slope in

lo g p

versus

lo g x

whose intercept is

lo g K_{H}

. For

C O_{2}

in water at

2 5^{\circ} C

the Henry constant

K_{H} \approx 1.6 \times 1 0^{3}

bar, so

lo g K_{H} > 0

and the intercept is positive. The correct plot is therefore the straight line of slope

1

cutting the

lo g p

axis at a positive value.

JEE Main · 2026 · 22 Jan 2026 · Shift 1 · Single correct option

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JEE Main · 2026 · 22 Jan 2026 · Shift 1 · Solutions

Solution

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