Find the void volume of fcc unit cell in $\mathrm{cm}^3$ if the volume of fcc unit cell $1.25 \times…

Find the void volume of fcc unit cell in $\mathrm{cm}^3$ if the volume of fcc unit cell $1.25 \times 10^{-22} \mathrm{~cm}^3$.
  1. $3.25 \times 10^{-23}$
  2. $2.16 \times 10^{-23}$
  3. $1.34 \times 10^{-23}$
  4. $4.20 \times 10^{-23}$

Solution

For fcc unit cell, packing efficiency $=74 \%$ $\therefore \quad$ Percentage of unoccupied space (void volume) $\begin{aligned} & =100-74=26 \% \\ & =1.25 \times 10^{-22} \mathrm{~cm}^3 \times \frac{26}{100} \\ & =3.25 \times 10^{-23} \mathrm{~cm}^3 \end{aligned}$

Asked in: MHT CET 2024 (16 May Shift 1)

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