QJEEAdv08Ch4e68: JEE Advanced 2008 Chemistry - Class 12 JEEAdv08Ch4e68 Solution: The empty space in this HCP unit cell is :

Question

Verified Solution • 2025–26 Session moderate

The empty space in this HCP unit cell is :

Accepted Answer

Packing fraction = $\frac{Total volume of unit cell}{Volume occupied}$

Substituting the values of occupied sphere and volume of the unit cell we have:

$\Rightarrow \frac{6 \times \frac{4}{3} \times π r^{3}}{24 \sqrt{2} r^{3}} = 0.74$

Rearranging and solving % occupied space = 74%

The space in the HCP unit cell = 100 $-$ 74 = 26%

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