Question

Number of unit cells in $10gNaCl$ is:

• A. $\frac{1.5}{58.5}\times {10}^{24}$
• B. $\frac{2.5}{58.5}\times {10}^{23}$
• C. $\frac{5.6}{58.5}\times {10}^{20}$
• D. $\frac{5.6}{58.5}\times {10}^{21}$

Answer 1

The correct option is A $\frac{1.5}{58.5}\times {10}^{24}$

Moles of $NaCl=\frac{10}{58.5}$

Number of molecules of $NaCl=\frac{10}{58.5}\times 6.023\times {10}^{23}$

In one unit cell $4$ molecules of $NaCl$ are present.

Number of unit cells $=\frac{10\times 6.023\times {10}^{23}}{58.5}\times \frac{1}{4}=\frac{1.5}{58.5}\times {10}^{24}$