Question

Which one of the statements given below concerning properties of solutions, describes a colligative effect?

• A. Boiling point of pure water decreases by the addition of ethanol
• B. Vapour pressure of pure water decreases by the addition of nitric acid
• C. Vapour pressure of pure benzene decreases by the addition of naphthalene
• D. Boiling point of pure benzene increases by the addition of toluene

Answer 1

The correct option is C Vapour pressure of pure benzene decreases by the addition of naphthalene

The decrease in vapour pressure of benzene by addition of naphthalene is an example of colligative property.
Change in vapour pressure of solvent or change in boiling point of solvent may also be due to formation of hydrogen bond and or interaction with between solvent molecule and solute molecule.