ANS:A - partial pressure of vapour in the mixture.

Partial pressure of vapor in a mixture refers to the pressure that the vapor would exert if it alone occupied the volume of the entire mixture at the same temperature. In other words, it's the pressure contributed by the vapor molecules to the total pressure of the mixture. Consider a mixture of gases, such as air, which contains various components including water vapor. Each gas in the mixture exerts its own pressure, known as its partial pressure. The partial pressure of the vapor is determined by its concentration in the mixture and follows Dalton's law of partial pressures, which states that in a mixture of non-reacting gases, the total pressure is the sum of the partial pressures of the individual gases. For example, if you have a closed container with air and water vapor, the total pressure inside the container is the sum of the partial pressure of the air and the partial pressure of the water vapor. Mathematically, the partial pressure of a component in a mixture can be calculated using the following formula: 𝑃partial=𝑋component×𝑃totalPpartial​=Xcomponent​×Ptotal​ Where:

• 𝑃partialPpartial​ is the partial pressure of the component,
• 𝑋componentXcomponent​ is the mole fraction of the component in the mixture,
• 𝑃totalPtotal​ is the total pressure of the mixture.