Question

Calculate the density (in g cm${}^{-3}$) of diamond from the fact that it has face-centered cubic structure with two atoms per lattice point and unit cell edge length of $3.569\mathring{A}$.

• A. $7.5$
• B. $1.7$
• C. $3.5$
• D. None of the above

Answer 1

The correct option is C $3.5$

$density=\frac{zM}{N_A\times (a{)}^3}$

For FCC, z=2

$density=\frac{(2\times 4)\times 12}{6\times {10}^{23}\times (3.569\times {10}^{-8}{)}^3}=3.5{\text{g cm}}^{-3}$