Question

Identify the correct statement from the following:

Options

• Vapour pressure of a solution containing a non-volatile solute is always less than vapour pressure of pure solvent.

• Boiling point of pure solvent is always greater than boiling point of it's solution containing a non-volatile solute.

• Liquids having greater intermolecular forces have lower boiling points.

• Vapour pressure of a solution containing a non-volatile solute is always greater than vapour pressure of pure solvent.

Answer 1

Vapour pressure of a solution containing a non-volatile solute is always less than vapour pressure of pure solvent.

Explanation:

Suppose, P₀ = Vapour pressure of pure solvent, P = Vapour pressure of solution

When nonvolatile solute is added to the pure solvent, it covers the surface are of the pure solvent, number of molecules going in vapour phase decreases between of which vapour pressure of solution is lowered as compare to pure solvent.

Lowering of vapour pressure,

∴ ΔP = P₀ - P