Which of the following statements is not correct?

Options

A. The ionic radii can be estimated by measuring the distances between cations and anions crystals.
B. A positive ion is always smaller than the corresponding atom.
C. Isoelectronic ions have identical sizes.
D. A negative ion is always begger than corresponding atom.

Answer

C

Explanation

Isoelectronic ions have different size on account of different magnitude of the nuclear charge or to be more appropriate, the nuclear charge per electron.
The internuclear distance between cations and anions is taken as the sum of the radii of cations and anions. during the formation of anions, nuclear charge remains the same but repulsion from additional `e^(-)s` enlarges the `e^(-)` cloud while removal of `e^(-)` reduces `e^(-)-e^(-)` repulsion, so the `e^(-)` cloud shirnks during the formation of cations.