Q. The freezing point depression of 0.001 m, $K_{x}\left\lbrack Fe(CN)_{6} \right\rbrack$is $7.10 \times 10^{- 3}K$. If for water, $k_{f}$ is 1.86 K Kg $mol^{- 1}$, value of $x$ will be

A) 4
B) 3
C) 2
D) 1
Explanation

(b)
$\mathrm{\Delta}x = i \times k_{f} \times m$
$7.10 \times 10^{- 3} = i \times 1.86 \times 0.001$
$i = 3.817$
$\because\ \alpha = \frac{i - 1}{n - 1}$
$\therefore 1 = \frac{3.817 - 1}{(x + 1) - 1}$
$x = 2.817 \approx 3$
$\therefore$ molecular formula of the compound is $K_{3}\lbrack Fe(CN)_{6}\rbrack$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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