Question

The number of unit cells in $58.5g$ of $\text{NaCl}$ is :

• A. $6\times {10}^{20}$
• B. $3\times {10}^{22}$
• C. $1.5\times {10}^{23}$
• D. $0.5\times {10}^{24}$

Answer 1

The correct option is C $1.5\times {10}^{23}$

We know that $1$ unit cell of $\text{NaCl}$ contains $4$ $\text{NaCl}$ particles.

$58.5$ g of $\text{NaCl}$ is one mole of $\text{NaCl}$ $=6.023\times {10}^{23}$ particles.

Therefore, the number of unit cells $=\frac{6.023\times {10}^{23}}{4}=1.5\times {10}^{23}$ in $58.5$ g of $\text{NaCl}$.

Therefore, option C is correct.