KH value for Ar(g), CO₂(g), HCHO (g) 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.

According to Henry’s law, the solubility of the gas in a given volume of liquid at a constant temperature is directly proportional to the pressure of gas exerted on the liquid. The relation is stated as follows, H p = k X x At constant pressure, the henry’s law constant H k value is inversely proportional to the mole fraction ‘x’. H 1 k x Therefore, the higher the value of H k lower is the solubility of a gas in the liquid, or the lower the value of H k higher is the solubility of the gas in the liquid. Here, HCHOhas the lower H k value followed by 4 CH , 2 CO and Ar .The correct order is