Question

If copper having density $\rho =9.0g/c{m}^3$ and atomic mass $63.5u$ crystallizes in face centered unit cell, then what is the value of edge length of the unit cell?

• A. $33.48pm$
• B. $144.1pm$
• C. $12.3pm$
• D. $360.5pm$

Answer 1

The correct option is D $360.5pm$

Density of unit cell is given by $\rho =\frac{zM}{a^3{N}_A}$
For FCC:
$Z=4$
On rearranging the equation for density
$a^3=\frac{zM}{\rho N_A}$
Substituting the given values:
$a^3=\frac{4\times 63.5}{9\times 6\times {10}^{23}}$

$a=360.5pm$