At room temperature, the solubility of which solute in water would be most affected by a change in pressure?
(1) methanol (3) carbon dioxide(2) sugar (4) sodium nitrate

 (3) carbon dioxide

Explanation: Solubility of solids and liquids is not affected by pressure as they are highly incompressible. Methanol is liquid, carbon dioxide is a gas, sugar is a solid and sodium nitrate is also a solid.

But solubility of gases is affected by pressure as they are compressible and the solubility is governed by Henry's law, which states that mass of gas dissolved in a given liquid ta constant temperature is directly proportional to the pressure of the gas present in equilibrium with the liquid.

Increase in pressure increases the solubility as increase in pressure would lead to decrease in volume of gas particles and hence more number of particles will be present per unit volume and as a result, the number of particles striking the surface of solution and entering the solution will increase. Thus solubility increases.