Question

An element X crystallizes in 3-D hexagonal closed packed structure having an edge length of $50\sqrt{6}pm$.
The height of the unit cell in pm will be :

Answer 1

In a hexagonal unit cell :


$h\text{is the height of the hcp unit cell}a\text{is the edge length of the unit cell}$
Since, :
$h=2\times \sqrt{\frac{2}{3}}\times ah=2\times \sqrt{\frac{2}{3}}\times 50\sqrt{6}h=200pm$