# NEET Chemistry The Solid State Questions Solved

BOARD

The unit cell of an element of atomic mass 108u and density 10.5 g cm-3 is a cube with edge length, 409 pm. Find the type of unit cell of the crystal. [Given : Avogadro's constant = 6.023 $×$ 1023 mol-1]

We know that Z = $\frac{{a}^{3}\rho ×{N}_{A}}{M}$

$\therefore$ Z = $\frac{\left(409×{10}^{-10}{\right)}^{3}×10.5×6.023×{10}^{23}}{108}$

$\frac{409×409×409×{10}^{-30}×10.5×6.023×{10}^{23}}{108}$

$\frac{423.68}{108}$ = 4

So it forms cubic- closed packed (ccp) lattice or fcc structure.

Difficulty Level:

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