Final answer:
The vapor pressure in the presence of applied pressure is given by Henry's law, which relates the solubility of a gas in a liquid to the partial pressure of the gas. Dalton's law describes the total pressure as the sum of the partial pressures, which is different from what the question asks.
Step-by-step explanation:
The vapor pressure in the presence of applied pressure is described by Henry's law. Henry's law states that the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. Therefore, this defines the relationship between the solubility of the gas in the liquid phase and the exerted vapor pressure. On the other hand, Dalton's law refers to the total pressure in a mixture of gases, indicating that it is the sum of the partial pressures of all the individual gases in the mixture.
Because we are dealing specifically with the vapor pressure of a substance when a pressure is applied, the correct answer to which law explains this is Henry's law. Dalton's law, in this context, would not be the relevant law for describing vapor pressure in the presence of applied pressure.