Question

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

Answer 1

4
As per the textbook, the radius ratio
Are in 4 different blocks
>0.144 -2
0.144 to 0.432 - 4
0.432 to 0.615 -6
<0.615 - 8

Answer 2

Answer: The correct answer is option (b).

Explanation:

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

0.155 to 0.225 for 3 coordination number

0.225 to 0.414 for 4 coordination number

0.414 to 0.732 for 6 coordination number

0.732 to 1 for 8 coordination number

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

The radius ratio of the given crystal lattice is 0.320 which is lying 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).