Question

An ionic crystal lattice has r+/r- radius ratio of 0.320, its co-ordination number is

Answer 1

Ans : 4

Explanation :- as you know,
For Tetrahedral ,
r⁺/r⁻ = 0.225

And for octahedral ,
r⁺/r⁻ = 0.414

and we know, we consider Tetrahedral , when ranging of r⁺/r⁻ between 0.225 ad 0.414 . here given r⁺/r⁻ = 0.320 , so, we consider Tetrahedral . And we know, coordination number of it is 4 . { One sphere is placed over 3 other sphere touching each other }