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COMEDK · Chemistry · 17. Solutions

\(5\text{ g}\) of a non-volatile, water-soluble compound \(X\) is dissolved in \(100\text{ g}\) of water (\(K_b = 0.52\text{ K kg mol}^{-1}\)). The elevation in boiling point is found to be \(1.3\text{ K}\). The molar mass of compound \(X\) is:

  1. A 20 g
  2. B 35 g
  3. C 40 g
  4. D 60 g
Verified Solution

Answer & Solution

Correct Answer

(A) 20 g

Step-by-step Solution

Detailed explanation

\(\Delta T_b = K_b \cdot m = \dfrac{K_b \cdot w_2}{M_2 \cdot w_1}\) \(M_2 = \dfrac{K_b \cdot w_2}{\Delta T_b \cdot w_1} = \dfrac{0.52 \times 5}{1.3 \times 0.1} = \dfrac{2.6}{0.13} = 20\) g/mol