Which statement best defines partial pressure in a gas mixture?

Which statement best defines partial pressure in a gas mixture?

• A. The total pressure of the gas mixture.
• B. The atmospheric pressure.
• C. The pressure that would be exerted by a gas if it alone occupied the volume.
• D. The pressure due to water vapour only.

Answer: (C)

Partial pressure is the pressure that a given gas would exert if it were the only gas present in the same volume at the same temperature. This captures how each component in a mixture contributes its own share to the total pressure, and the total pressure is the sum of all those individual pressures (Dalton’s law). It is not the total pressure of the mixture, nor atmospheric pressure, nor exclusively the pressure from water vapor.

Partial pressure is the pressure that a given gas would exert if it were the only gas present in the same volume at the same temperature. This captures how each component in a mixture contributes its own share to the total pressure, and the total pressure is the sum of all those individual pressures (Dalton’s law). It is not the total pressure of the mixture, nor atmospheric pressure, nor exclusively the pressure from water vapor.