Question

The weight of $1\times {10}^{22}$ molecules of $CuS{O}_4\cdot 5H_{2}O$ is :

• A. $4.14$ g
• B. $5.14$ g
• C. $6.14$ g
• D. $7.14$ g

Answer 1

The correct option is A $4.14$ g

Weight of $6.023\times {10}^{23}$ (Avogadro's number) $=$ Mw of $CuS{O}_4\cdot 5H_{2}O=249$ g $=$ $1$ mol of $CuS{O}_4\cdot 5H_{2}O$

Therefore, weight of $1\times {10}^{22}$ molecules of $CuS{O}_4\cdot 5H_{2}O$
$=\frac{249\times 1\times {10}^{22}}{6.023\times {10}^{23}}=4.14$ g