How many molecule are present in 12 L of liquid ${\mathrm{CCl}}_4?$ The density of the liquid is 1.59 g ${\mathrm{cm}}^{-3}?$

$\begin{array}{l}1\mathrm{cc}\mathrm{of}{\mathrm{CCl}}_4\mathrm{contains}1.59\mathrm{g}\mathrm{of}\mathrm{it}\\ \therefore 12\mathrm{L}\mathrm{of}\mathrm{liquid}{\mathrm{CCl}}_4\mathrm{will}\mathrm{contain}=12\times 1000\times 1.59=159\times 120\\ \mathrm{molecular} \mathrm{wt}. \mathrm{of} {\mathrm{CCl}}_4=12+4(35.5)=154\mathrm{g}\\ \mathrm{number} \mathrm{of} \mathrm{molecules}=\mathrm{n}\times 6.023\times {10}^{23}=\frac{159\times 120}{154}\times 6.023\times {10}^{23}\\ =0.744\times {10}^{26}\end{array}$