According to Henry's law, what determines the amount of gas that will dissolve in a liquid?

The correct answer is rooted in the principles of Henry's law, which states that the amount of a gas that dissolves in a liquid at a given temperature is directly proportional to the partial pressure of that gas above the liquid. This means that as the partial pressure increases, more gas molecules will be forced into the liquid until the system reaches equilibrium. Essentially, higher pressures push more gas into the solution, thus increasing the solubility of the gas in the liquid.

In contrast, factors like the temperature of the liquid can also affect gas solubility, but they do not define the relationship outlined in Henry's law. Similarly, the viscosity of the liquid influences how substances move through it and can affect diffusion rates, but it does not directly dictate the amount of gas dissolving. The volume of the gas present can relate to the total amount available for dissolution, but it is the partial pressure that governs how much of that gas can actually dissolve at any given moment. Therefore, the key determinant of gas solubility in this context is the partial pressure of the gas.