Question

An ionic crystal lattice has r+/r- radius ratio of 0.320, its co-ordination number is-
a) 3
b) 4
c) 6
d) 8

Answer 1

really answer is unknown but probably i choose option a

Answer 2

Answer: The correct answer from the given options is option (b).

Explanation:

Radius ratio = $\frac{\text{Radius of the cation}}{\text{Radius of the anion}}$

0.155 to 0.225 for coordination number 3

0.225 to 0.414 for coordination number 4

0.414 to 0.732 for coordination number 6

0.732 to 1 for coordination number 8

Given radius ratio of the ionic crystal lattice = $\frac{r_+}{r_-}=0.320$

The radius ratio of the given crystal lattice is 0.320. 0.320  lies in between the range of 0.225 to 0.414 radius ratio for coordination number 4.

The coordination number is 4. Hence,the correct answer is option (b).