Question

In a CCP structure of compound XY, atom X ispresent at octahedral voids. The ratio of 6th C. N.and 3rd C.N. for an atom X located at body-centre is​

Answer 1

answer : 3

explanation : In a CCP structure of compound XY, atom X is present at octahedral voids. we know, co-ordination of octahedral void is 6. octahedral voids appear at four adjacent edge-centres of each of six adjacent units cells.
so, number of octahedral voids = 6 × 4 = 24

6th co-ordination of atom X will be 24,‘X’ atoms present at four adjacent edge - centres of each of six adjacent unit cells.

co-ordination of body-centered is 8 and also co-ordination of atom placed at corner of unit cell is 8.
3rd co-ordination of atom X will be 8,‘Y’ atoms present at all corners of unit cell.

so, $\frac{6^{th}C.N}{3^{rd}C.N}=\frac{24}{8}=3$