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Question

Question: Fraction of total volume occupied by atoms in a simple cube is...

Fraction of total volume occupied by atoms in a simple cube is

A

π2\frac{\mathbf{\pi}}{\mathbf{2}}

B

3π8\frac{\sqrt{3}\pi}{8}

C

2π6\frac{\sqrt{2}\pi}{6}

D

π6\frac{\pi}{6}

Answer

π6\frac{\pi}{6}

Explanation

Solution

In a simple cubic system, number of atoms a = 2r

\therefore Packing fraction

=Volume occupied by one atomVolume of unit cell=43πr3a3=43πr3(2r)3=π6= \frac{\text{Volume occupied by one atom}}{\text{Volume of unit cell}} = \frac{\frac{4}{3}\pi r^{3}}{a^{3}} = \frac{\frac{4}{3}\pi r^{3}}{(2r)^{3}} = \frac{\pi}{6}