Question

The number of unit cells in $58.5$ g of $NaCl$ is nearly ?

• A. $6\times {10}^{23}$
• B. $3\times {10}^{22}$
• C. $1.5\times {10}^{23}$
• D. $0.5\times {10}^{24}$

Answer 1

Answer: (C)

$1.5\times {10}^{23}$

$NaCl$ crystalline in FCC structure i.e., $4$ molecules of $NaCl$ is present in one unit cell.

Moles of $NaCl=\frac{58.5}{58.5}=1$

Moles of unit cell $=\frac{1}{4}=0.25$

Total number of unit cells $=\frac{1}{4}\times 6\times {10}^{23}=1.5\times {10}^{23}$ cells