Question

In a face centred cubic arrangement of A and B atoms whose A atoms are at the corner of the unit cell and B atoms at the face centred. One of the A atom is missing from one corner in unit cell. The simplest formula of compound is:
(a) A7B3
(b) AB3
(c) A7B24
(d) None of these

answer it With EXPlanation

Answer 1

A7B24

Explanation:

there are total 8 corners and each contributes one eight to the unit cells

one of the A atom is missing from one corner in the unit cells. so there are 7'A' atoms with total contribution

7×1/8=7/8

B atom are the faces centre there are six faces centre each contributes one half to the unit cells

total contribution=6×1/2=3

A:B= 7/8:3=7:24

the simplest formula of the compound is A7B24