The correct statement in the following is

Options

A. The ionic crystal of `AgBr` has schottky defect
B. The unit cell having crystal parameters, `a = b ne c, alpha = beta = 90^(@) , gamma = 120^(@)` is hexagonal
C. In ions compound having frenkel defect the ratio `(gamma_(+))/(gamma_(-))` is high
D. The coordination number of `Na^(+)` ion in `NaCI` is `4`

Answer

b

Explanation

A crystal system is haxagojnal if the unit cells have `a= b!= c`axial ratio `alpha = beta = 90^(@) , gamma = 120^(@)` axial angles.