JEE Main 2022 · 25 Jul · Shift 1 · Chemistry Q63

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ChemistrySingle correct+4 / -1Question 63 of 90

The depression in freezing point observed for a formic acid solution of concentration 0.5 mL L $^{-1}$ is 0.0405°C. Density of formic acid is 1.05 g mL $^{-1}$ . The Van't Hoff factor of the formic acid solution is nearly : (Given for water $k_f=1.86$ k kg mol $^{-1}$ )

0.8

1.1

1.9

2.4

Answer and worked solution

Official answer: C

Molality. $\frac{0.5\times1.05}{46}\approx0.0114$ m, so $\Delta T_f$ expected $0.0212$ °C.

Factor $\frac{0.0405}{0.0212}\approx1.9$ .

(C)

Topics:van't Hoff factor Colligative properties

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JEE Main 2022 · 25 Jul · Shift 1, Chemistry question 63