JEE Main & Advanced Chemistry Solutions / विलयन Sample Paper Topic Test - Solutions

Boiling point of chloroform was raised by 0.323 K, when 0.5143 g of anthracene was dissolved in 35 g of chloroform. Molecular mass of anthracene is: (\[{{K}_{b}}\] for \[CHC{{l}_{3}}\]= 3.9 kg/mol )

A) 79.42 g/mol

B) 132.32 g/mol

C) 177.42 g/mol

D) 242.32 g/mol

Correct Answer: C

Solution :

[c] Here: \[\Delta {{T}_{b}}\] = 0.323 K

w = weight of Anthracene.

W = weight of chloroform

\[{{K}_{b}}\]= Molal elevation constant (3.9 K-kg/mol)

\[m=\frac{{{K}_{b}}\times w\times 1000}{W\times \Delta {{T}_{b}}}=\frac{3.9\times 0.5143\times 1000}{0.323\times 35}\]

\[=177.42g/mol\]