The concentration of gas in a solution is directly proportional to the partial pressure of the gas above the solution.

• A. Raoult's Law
• B. Henry's Law
• C. Colligative properties
• D. Boiling Point Elevation

Answer: (B)

Henry's Law states that at a given temperature, the amount of gas that dissolves in a liquid is directly proportional to the partial pressure of the gas above the liquid. In other words, C = kH × Pgas. This means increasing the partial pressure of the gas increases its dissolved concentration until equilibrium is reached, with the proportionality constant kH depending on temperature.

This concept helps explain why gases dissolve more readily under higher pressures and how solubility drops as temperature rises for most gases. It’s the correct framework for the statement, distinguishing it from other ideas: Raoult's Law concerns how the presence of a solute lowers the solvent’s vapor pressure in a solution, not gas dissolution in a liquid; colligative properties involve changes in properties like boiling point or freezing point due to the number of dissolved particles, not a direct link between dissolved gas and gas-phase pressure; boiling point elevation is one such colligative effect, again not about gas dissolution.