Question

The freezing point of a solution prepared from
1.25 gm of a non electrolyte and 20 gm of water is
271.94 K. If K???? is 1.86 Kmol⁻¹. Then the molar
mass of the solute will be nearly :
(a) 109 (b) 106
(c) 115 (d) 93

Answer 1

Explanation:

d) is the correct option

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Answer 2

(d) 93

Explanation:

ΔT(f) = 1000 K(f) * W2 / (Mw2 * W1)

From given info, we get

ΔT(f) = 273 - 271.9 = 1.25

So 1.25 = 1000 * 1.86 * 1.25 / (Mw2 * 20)

Mw2 = (1000 * 1.86 * 1.25) / (1.25 * 20) = 50 * 1.86 = 93

Hence Option D is the answer.