Question

The total weight of ${10}^{22}$ molecular units of $CuS{O}_4.5H_{2}O$ is nearly:

• A. 4.144 g
• B. 4.5 g
• C. 24.95 g
• D. 41.45 g

Answer 1

Answer: (A)

4.144 g

Molecular mass of $CuS{O}_4.5H_{2}O$ = 249.5

So, mass of $6.023\times {10}^{23}$ molecules = 249.5

So, mass of ${10}^{22}$ molecules = $\frac{249.5}{6.023\times {10}^{23}}\times {10}^{22}=4.144g$