Which law states that the total pressure of a gas mixture is equal to the sum of the partial pressures of its individual gases?

A. Henry's: Henry’s law explains how the solubility of a gas in a liquid is proportional to its partial pressure above the liquid. It is essential for understanding how oxygen and carbon dioxide dissolve in blood, but it does not describe how total pressure in a gas mixture is determined.

B. Dalton's: Dalton’s law of partial pressures states that the total pressure of a gas mixture is the sum of the partial pressures of each individual gas. This law is crucial in respiratory physiology, as it allows calculation of oxygen, carbon dioxide, and nitrogen tensions in alveolar air and blood.

C. Charles's: Charles’s law describes the direct relationship between gas volume and temperature at constant pressure. While it explains how gas expands when heated, it does not relate to the additive pressures of multiple gases in a mixture.

D. Valsalva's: The Valsalva maneuver is a physiological action involving forceful exhalation against a closed glottis, affecting intrathoracic and cardiovascular pressures. It is unrelated to gas laws and does not provide information about partial or total pressures.

E. Boyle's: Boyle’s law states that the volume of a gas varies inversely with pressure at constant temperature. It explains how compression or expansion of a single gas affects its volume, but it does not address the total pressure of a mixture of gases.