Start free

Chemistry · Solutions and Colligative Properties

JEE Main 2025 — 28 January, Morning Shift — Question 40

What is the freezing point depression constant of a solvent, 50 g of which contain 1 g non volatile solute (molar mass 256 g mol−1256 \mathrm{~g} \mathrm{~mol}^{-1} ) and the decrease in freezing point is 0.40 K ?

  1. Option A:

    5.12 K kg mol−15.12 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}

    Correct
  2. Option B:

    4.43 K kg mol−14.43 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}

  3. Option C:

    1.86 K kg mol−11.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}

  4. Option D:

    3.72 K kg mol−13.72 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}

Answer: A

Step-by-step solution

ΔTf=Kb.m\Delta \mathrm{T}_{\mathrm{f}}=\mathrm{K}_{\mathrm{b}} . \mathrm{m}

0.4=Kb125650×10−30.4=\mathrm{K}_{\mathrm{b}} \frac{\frac{1}{256}}{50 \times 10^{-3}}

Kb=5.12 K kg/mol\mathrm{K}_{\mathrm{b}}=5.12 \mathrm{~K} \mathrm{~kg} / \mathrm{mol}

Answer key and solution verified before publishing.

Practise Solutions and Colligative Properties

Start with this question, then two more from the same chapter — with a tutor that explains every step. Free.

Solve a similar one free
Exam
JEE Main 2025
Paper
28 January, Morning Shift
Subject
Chemistry
Chapter
Solutions and Colligative Properties
Topic
Abnormal Colligative Properties - van't Hoff Factor
What is the freezing point depression constant of a solvent, 50 g of… | JEE Main 2025 PYQ with Solution · DhiX AI