Medium INTEGER +4 / -1 PYQ · JEE Mains 2023

The molality of a $10 \%(\mathrm{v} / \mathrm{v})$ solution of di-bromine solution in $\mathrm{CCl}_{4}$ (carbon tetrachloride) is '$x$'. $x=$ ____________ $\times 10^{-2} ~\mathrm{M}$. (Nearest integer)

[Given : molar mass of $\mathrm{Br}_{2}=160 \mathrm{~g} \mathrm{~mol}^{-1}$

atomic mass of $\mathrm{C}=12 \mathrm{~g} \mathrm{~mol}^{-1}$

atomic mass of $\mathrm{Cl}=35.5 \mathrm{~g} \mathrm{~mol}^{-1}$

density of dibromine $=3.2 \mathrm{~g} \mathrm{~cm}^{-3}$

density of $\mathrm{CCl}_{4}=1.6 \mathrm{~g} \mathrm{~cm}^{-3}$]

Answer (integer) 139

Solution

Mass of $10 \mathrm{~mL}$ of $\mathrm{Br}_2=10 \times 3.2=32 \mathrm{gm}$ <br/><br/>Mass of $90 \mathrm{~mL}^{\mathrm{L}} \mathrm{CCl}_4=90 \times 1.6=144 \mathrm{gm}$ <br/><br/>Molality of $\mathrm{Br}_2$ solution in $\mathrm{CCl}_4$ <br/><br/>$$ \begin{aligned} & =\frac{32 \times 1000}{160 \times 144} \\\\ & =1.39 \mathrm{M} \\\\ & =139 \times 10^{-2} \end{aligned} $$

About this question

Subject: Chemistry · Chapter: Some Basic Concepts of Chemistry · Topic: Mole Concept

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