Question

Select the correct relation regarding the ionic radii of given ions:

• A. $T{i}^{4+}<M{n}^{7+}$
• B. ${}^{35}C{l}^{-}<{}^{37}C{l}^{-}$
• C. $K^{+}>C{l}^{-}$
• D. $P^{3+}>P^{5+}$

Answer 1

The correct option is D $P^{3+}>P^{5+}$

Option (a): $T{i}^{4+}<M{n}^{7+}$ is the correct order of size. As there are more protons in the nucleus on $M{n}^{7+}$ as compared to that of $T{i}^{4+}$. More protons means more $Z$-effective over the valence electrons and hence small size of the ion.
Option (b): ${}^{35}C{l}^{-}<{}^{37}C{l}^{-}$ : Isotopes with the same charge have the same size because isotopes differ in compositions of nuclei or say in the number of neutrons which do not affect the atomic/ionic radius.
Option (c): $K^{+}<C{l}^{-}$ is the correct order. Among isoelectronic species, anion has greater size than cation.
Option (d): $P^{3+}>P^{5+}$ is the correct order. For the same elements, lower the positive charge, larger the ions.