Question

Choose the correct option (s) for a liquid kept in closed vessel at constant temperature:

• A. A $\to$ Evaporation
• B. B $\to$ Condensation
• C. A $\to$ Condensation
• D. B $\to$ Evaporation

Answer 1

Answer: (A), (B)

The correct options are
A A $\to$ Evaporation
B B $\to$ Condensation

In the beginning, the rate of evaporation is high. However, as more and more molecules with enough energy leave the liquid, the rate of evaporation decreases with time. On the other hand, as the number of molecules in the vapour phase is very small in the beginning, the rate of condensation is very low. However, with the passage of time, as the number of molecules in the vapour phase increases, the rate of condensation also increases. Ultimately, a stage is reached when the rate of evaporation becomes equal to the rate of condensation, i.e., equal number molecules leave and re-enter the liquid at the same time.This state is called the state of equilibrium.