Chemistry - Solid State Question with Solution | TestHub

P is in f.c.c. lattice
Number of atoms$\text{=}\text{atom}\text{at}\text{corner}\text{×}\frac{\text{1}}{\text{8}}\text{+}\text{atoms}\text{at}\text{faces}\text{×}\frac{\text{1}}{\text{2}}$
$\mathrm{P}=8\times \frac{1}{8}+6\times \frac{1}{2}=4$
Total tetrahedral voids$=8$
As Q are at T.V.
So$\mathrm{Q}=8$
Number of octahedral voids$=4$
$\mathrm{R}=\frac{1}{2}\times 4=2$
So,$\mathrm{P}=4,\mathrm{Q}=8,\mathrm{R}=2$
Hence the formula of solid is${\mathrm{P}}_4{\mathrm{Q}}_8{\mathrm{R}}_2$or${\mathrm{P}}_2{\mathrm{Q}}_4\mathrm{R}$