Question

Which one of the following is the smallest in size?(a) N³⁻ (b) O²⁻ (c) F⁻ (d) Na⁺

Answer 1

The size depends upon the radius.

The ionic radii of isoelectronic species increases with a decrease in the magnitudes of nuclear charge.

The arrangement of the given species in order of their increasing nuclear charge is as follows:

N³⁻ <O²⁻ < F⁻ < Na⁺

Nuclear charge = +7 +8 +9 +11

Therefore, the arrangement of the given species in order of their increasing ionic radii is as follows:

Na⁺>F⁻>O²⁻>N³⁻

So,N³⁻ is the smallest one.