Question

In which of the following compound size of cation to anion ratio is minimum:

• A. CsF
• B. LiI
• C. LiF
• D. CsI

Answer 1

Answer: (B)

LiI

Answer 2

To minimize the cation to anion size ratio ($r_{cation}/r_{anion}$), the cation size must be the smallest and the anion size must be the largest. Among the given options, Li$^+$ is the smallest cation and I$^-$ is the largest anion. Therefore, LiI has the minimum cation to anion size ratio.