Question

Which of the following changes decrease the vapour pressure of water kept in a sealed vessel?

• A. Decreasing the quantity of water
• B. Adding salt to water
• C. Decreasing the volume of the vessel to one half
• D. Decreasing the temperature of water

Answer 1

Answer: (B), (D)

The correct options are
B

Adding salt to water

D

Decreasing the temperature of water

When salt is added, less surface area is available for the solvent to vaporize and hence, vapour pressure decreases. Vapour pressure also decreases with the decrease in temperature because the kinetic energy of the molecules decreases.