The packing fraction of a simple cubic structure is `pi//6`. Prove. 

Explanation

In a simple cube, the face edge length, a = 2r
Number of atoms present in one unit cell = 1 Packing fraction `= ("Volume occupied by atoms")/("Volume of the unit cell")=((4)/(4)pir^(3))/(a^(3))=(4)/(3)(pir^(3))/((2r)^(3))=(pi)/(6)`