Question

Which of the following statement(s) is/are true?
i. Adding a solute raises the vapor pressure & boiling point.
ii. The change in boiling & freezing point depends on molality.
iii. The number of solute particles in a solvent is an important factor in determining the boiling point elevation.

• A. i only
• B. ii only
• C. i and ii
• D. ii and iii
• E. i, ii and iii

Answer 1

Answer: (D)

ii and iii

Adding a solute lowers the vapour pressure & raises the boiling point.
The change in boiling & freezing point depends on molality.
The depression in the freezing point
$\Delta T_f=i\times K_f\times m$
The elevation in the boiling point
$\Delta T_b=i\times K_b\times m$
Here, m is the molality and ${}^{\prime }{i}^{\prime }$ is the vant Hoff factor.
The number of solute particles in a solvent is an important factor in determining the boiling point elevation. The boiling point elevation is a colligative property.