State Henry's law and identify the type of systems it applies to.

• A. C = p / k_H (solubility inverse to pressure); applies to dilute solutions.
• B. C = k_H p (solubility proportional to partial pressure); applies to dilute solutions at constant temperature.
• C. P = k_H C (partial pressure proportional to concentration); applies to all gases.
• D. C = k_H / p; applies to saturated vapors.

Answer: (B)

Henry's law describes how a gas and a liquid reach equilibrium at a fixed temperature: the amount of gas dissolved in the liquid is proportional to the gas’s partial pressure above the liquid. The proportionality constant, k_H, depends on the specific gas–solvent pair and the temperature. This gives the relation C = k_H p, where C is the dissolved concentration and p is the partial pressure of the gas.

This applies to dilute solutions at constant temperature because, in that regime, gas molecules dissolve without significantly affecting each other or the solvent, so the relationship remains linear. If you push to higher pressures or concentrations, or change temperature, deviations occur and Henry’s law no longer holds as stated.

So the correct view is the dissolved concentration increases linearly with the partial pressure, with the slope given by Henry’s constant, for dilute solutions at a fixed temperature. The other forms misstate the direction of the relationship or the conditions under which it applies (not all gases, not all conditions, and not for saturated vapors).