Question

A mineral having formula AB2 crystallises in CCP lattice, with A atoms occupying lattice points. Hence coordination number of A and B atoms are(a) 4,8(b) 4,4(c) 8,8(d) 8,4

Answer 1

Answer:

option d is correct.

Explanation:

Here A atom coordination number is 8 so it is cubic coordination.

And B atom coordination number is 4 so it is Tetrahedral coordination.

AB2 type crystal structure (CaF2):

Blue-Ca

Yellow-F

Co ordination number of A(For example Ca)= 8 (White one is surrounded by 8 neighbours) .

Co ordination number of B(For example F)= 4 (yellow one is surrounded by 4 neighbours).