The density of iridium is 22.4 g cm^ -3 . The unit cell of iridium...

For an fcc unit cell, the number of atoms per unit cell is $Z = 4$.

The density of the unit cell is given by the formula:

$d = \dfrac{Z \times M}{N_A \times V}$

Rearranging the formula to solve for the volume $V$ of the unit cell:

$V = \dfrac{Z \times M}{N_A \times d}$

Substituting the given values:

$V = \dfrac{4 \times 192.2}{6.022 \times 10^{23} \times 22.4}$

$V = \dfrac{768.8}{134.89 \times 10^{23}}$

$V = 5.7 \times 10^{-23}$ cm^3$<br><br>Answer:$5.7 \times 10^{-23}$cm^3$