The correct statement about $\mathrm{I}{\mathrm{Cl}}_5$ and $\mathrm{I}{\mathrm{Cl}}_4^{-}$ is:

• A

  $\mathrm{I}{\mathrm{Cl}}_5$ is trigonal bipyramidal and $\mathrm{I}{\mathrm{Cl}}_4^{-}$ is tetrahedral.
• B

  Both are isostructural.
• C

  $\mathrm{I}{\mathrm{Cl}}_5$ is square pyramidal and $\mathrm{I}{\mathrm{Cl}}_4^{-}$ is tetrahedral.
• Correct answer
  D

  $\mathrm{I}{\mathrm{Cl}}_5$ is square pyramidal and $\mathrm{I}{\mathrm{Cl}}_4^{-}$ is square planar.

Hence, the correct answer is option: 'D'.