Question

For an ionic crystal of general formula $\text{AX}$ and co-ordination number $6$, the value of radius ratio will be:

• A. greater than $0.73$
• B. in between $0.414$ and $0.732$
• C. in between $0.22$ and $0.41$
• D. less than $0.22$

Answer 1

The correct option is B in between $0.414$ and $0.732$

Since the general formula is $\text{AX}$ with coordination number $6$, the crystal could be considered as $\text{NaCl}$. Thus, it is evident that the ratio lies between $0.414$ and $0.732$ because of its octahedral structure.

The value ranging between $0.414$ and $0.732$ is obtained by dividing the radius of positive ion by that of negative ion.