Q1: Humidification involves mass transfer between a pure liquid phase and a fixed gas, which is

ANS:A - insoluble in the liquid

Humidification involves mass transfer between a pure liquid phase and a fixed gas, which is soluble in the liquid. In humidification, the fixed gas (typically air) comes into contact with a liquid (usually water) to increase the humidity of the air. Water vapor from the liquid phase transfers into the gas phase until equilibrium is reached. This process occurs because the gas is soluble in the liquid phase, meaning that it can dissolve into the liquid to some extent. As the gas dissolves into the liquid, it increases the concentration of the gas in the liquid phase, leading to an increase in humidity. This mass transfer process continues until equilibrium is reached, where the partial pressure of the gas in the gas phase is equal to the vapor pressure of the liquid phase at the given temperature. Therefore, in humidification, the fixed gas is soluble in the liquid, allowing for the transfer of mass (water vapor) between the two phases.