Chemistry - Solid State Question with Solution | TestHub

Number of unit cells in 1 g NaCl:

$$N=\frac{1}{58.5}\times \frac{6\times 10^{23}}{4}=2.56\times 10^{21}$$

(FCC NaCl has $Z=4$).

Since the crystal is a perfect cube, unit cells along one edge = $N^{1/3}$.

$N^{1/3}=(2.56\times 10^{21}{)}^{1/3}\approx 1.37\times 10^7$

(Using $\frac{300}{117}=(1.37{)}^3$).

Answer: $1.37\times 10^7$ unit cells along any one axis.