Some Basic Concepts of Chemistry - Result Question 36 — JEE PYQ Chapterwise

Answer:

Correct Answer: 36. (4.14 g)

Solution:

36. Molar mass of $CuSO _4 \cdot 5 H _2 O$

$\begin{aligned} & =63.5+32+4 \times 16+5 \times 18 \\ & =249.5 g \end{aligned}$

Also, molar mass represents mass of Avogadro number of molecules in gram unit, therefore

$\because 6.023 \times 10^{23}$ molecules of $CuSO _4 \cdot 5 H _2 O$ weigh $249.5 g$

$\therefore 10^{22}$ molecules will weigh $\frac{249.5}{6.023 \times 10^{23}} \times 10^{22}=4.14 g$