The unit cell of a binary compound of A and B metals has a ccp structure with A atoms occupying the corners and B atoms occupying the centres of each faces of the cubic unit cell. If during the crystallisation of this alloy, in the unit cell two A atoms are missed, the overall composition per unit cell is :

Options

A. `AB_(6)`
B. `AB_(4)`
C. `AB_(8)`
D. `AB_(24)`

Answer

B

Explanation

Total no. of A atoms = 8 − 2 = 6
Total no. of B atoms = 6
Effective no. of A atoms = `6 xx 1//8 = 3//4`
Effective no. of B atoms = `6 xx 1/2 = 3`
Composition per unit cell `A: B = 3//4 : 3 = 1 : 4` or `AB_(4)`