Select the order of increasing solubility of given gases in water at 293 K:
(A) \( O_2 (K_H = 34.86\, kbar) \)
(B) \( He (K_H = 144.97\, kbar) \)
(C) \( N_2 (K_H = 76.48\, kbar) \)
(D) \( H_2 (K_H = 69.16\, kbar) \)
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (B), (C), (D), (A)
Henry’s law states that the partial pressure of a gas over a solution is proportional to its mole fraction in the solution:
\( \displaystyle p = K_H\,x \quad \Rightarrow \quad x = \frac{p}{K_H} \)
At the same pressure and temperature, the mole fraction of dissolved gas, its solubility, is inversely proportional to \( K_H \). The higher the value of \( K_H \), the lower the solubility.
(A) \( \ce{O2} \): \( K_H = 34.86 \) kbar, the smallest value: most soluble.
(B) He: \( K_H = 144.97 \) kbar, the largest value: least soluble.
(C) \( \ce{N2} \): \( K_H = 76.48 \) kbar.
(D) \( \ce{H2} \): \( K_H = 69.16 \) kbar.
In increasing order of solubility (decreasing \( K_H \)):
\( \displaystyle \ce{He}\,(144.97) \lt \ce{N2}\,(76.48) \lt \ce{H2}\,(69.16) \lt \ce{O2}\,(34.86) \)
NCERT (2026-27 edition):
Solubility of a Gas in a Liquid – …
