Periodic Classification and Periodic Properties - Result Question 21

18. Which one of the following is the smallest in size?

(a) $N^{3-}$

(b) $O^{2-}$

(c) $F^{-}$

(d) $Na^{+}$

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Answer:

Correct Answer: 18. (a)

Solution:

  1. Among isoelectronic species, the relation in size is

$ \text { cation }<\text { neutral }<\text { anion } $

Hence, $Na^{+}$has smallest size.