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← JEE Main 2022 · 28 Jul · Shift 1
ChemistryInteger+4 / -1Question 84 of 90

JEE Main 2022 · 28 Jul · Shift 1, Chemistry question 84

150 g of acetic acid was contaminated with 10.2 g ascorbic acid (C6H8O6)(\mathrm{C_6H_8O_6}) to lower down its freezing point by (x×10−1)(x\times10^{-1})°C. The value of xx is ______. (Nearest integer)

[Given KfK_f = 3.9 K kg mol−1^{-1}; molar mass of ascorbic acid = 176 g mol−1^{-1}]

Answer and worked solution

Official answer: 15

Molality 10.2/1760.150=0.386\frac{10.2/176}{0.150}=0.386, so ΔTf=3.9×0.386=1.51\Delta T_f=3.9\times0.386=1.51°C ≈15×10−1\approx15\times10^{-1}.

Answer: 15