JEE Main levelSingle correct optionDifficulty 2 of 3si085
Distillation under reduced pressure lowers the boiling temperature of a liquid because
Athe intermolecular forces in the liquid become weaker at low pressure
Bthe vapour pressure of the liquid at a given temperature increases when the pressure is reduced
Cthe heat of vapourisation becomes zero
Da liquid boils when its vapour pressure becomes equal to the external pressure
Answer: D
Boiling begins when the vapour pressure equals the pressure above the liquid. At lower external pressure this is reached at a lower temperature, so thermally sensitive liquids can be distilled without decomposition.