ANS:A - 1

When the psychrometric ratio is 1, the adiabatic saturation temperature and wet bulb temperature become equal. The psychrometric ratio (ΨΨ) is defined as the ratio of the difference between the enthalpy of the vapor in the air to the difference between the enthalpy of the vapor and the enthalpy of the dry air. Mathematically, it can be expressed as: Ψ=ℎ𝑣−ℎ𝑑𝑎ℎ𝑣−ℎ𝑑Ψ=hv​−hd​hv​−hda​​ Where:

• ℎ𝑣hv​ = specific enthalpy of the vapor in the air
• ℎ𝑑𝑎hda​ = specific enthalpy of the dry air
• ℎ𝑑hd​ = specific enthalpy of the dry air at the wet bulb temperature

When the psychrometric ratio is 1, it indicates that the air is saturated with water vapor. In this case, the air is at its adiabatic saturation temperature, and the wet bulb temperature, which is the temperature indicated by a wet thermometer bulb exposed to the air flow, will be equal to the adiabatic saturation temperature. Therefore, when the psychrometric ratio is 1, the adiabatic saturation temperature and wet bulb temperature become equal.