Which of the following statements is not correct ?

Options

A. The number of carbon atoms in an unit cell of diamond is 4
B. The number of Bravais lattices in which a crystal can be categorized is 14
C. The fraction of the total volume occupied by the atoms in a primitive cell is 0.48
D. Molecular solids are generally volatile

Answer

C

Explanation

Packing fraction for a cubic unit cell is
`f=(zxx4//3pir^(3))/(d^(3))`
Here a = edge length, r = radius of cation and anion
Efficiency of packing in simple cubic or primitive cell `= pi/6 = 0.52`
i.e., `52%` of unit cell is occupied by atoms and `48%` is empty.