Question

The correct order of increasing radii are

• A. $B{e}^{+2},M{g}^{+2},N{a}^{\oplus }$
• B. $K^{\oplus },C{a}^{+2},S^{-2}$
• C. $O^{-2},F^{-},N^{-3}$
• D. $S^{-2},O^{2-},A{s}^{3-}$

Answer 1

The correct option is A

$B{e}^{+2},M{g}^{+2},N{a}^{\oplus }$

$B{e}^{+2}$ ion is of $2^{nd}$ period whereas $M{g}^{+2}$ and $N{a}^{+}$ ion are $3^{rd}$ period ions. $3^{rd}$ period ions have greater size than $2^{nd}$ period ions.Among the ions of same period larger the positive charge,smaller is the ion