KH value for Ar(g), CO2(g), HCHO (g) and CH4(g) are 40.39, 1.67, 1.83×10–5 and 0.413 respectively.

Arrange these gases in the order of their increasing solubility.



The higher the Kh lower is the solubility of the gas in the solvent.


More pressure is required to dissolve a gas with higher Kh.


Thus, the correct increasing order of the solubility is Ar < CO2 < CH4 < HCHO.


Thus, Option(iii) is the correct answer.

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