Some Basic Concepts of Chemistry - Result Question 9 — JEE PYQ Chapterwise

Answer:

Correct Answer: 9. (b)

Solution:

Molarity $=\dfrac{\text { Number of moles of solute }(n)}{\text { Volume of solution (in L) }}$

Also, $\quad n=\dfrac{w _B(g)}{M _B\left(g mol^{-1}\right)}$

$\therefore \quad$ Molarity $=\dfrac{w _B / M _B}{V}$

Given, $w _B=$ mass of solute $(B)$ in $g$

$ M _B=\text { Gram molar mass of } B\left(C _{12} H _{22} O _{11}\right)=342 g mol^{-1} $

Molarity $=0.1 M$

Volume $(V)=2 L$

$\Rightarrow \quad 0.1=\dfrac{w _B / 342}{2} \Rightarrow w _B=0.1 \times 342 \times 2 g=68.4 g$