The pairs among $\mathrm{A}=[\mathrm{SO}_{3}^{2-}, \mathrm{CO}_{3}^{2-}]$, $\mathrm{B}=[\mathrm{O}_{2}^{2-}, \mathrm{F}_{2}]$, $\mathrm{C}=[\mathrm{CN}^{-}, \mathrm{CO}]$, $\mathrm{D}=[\mathrm{NH}_{3}, \mathrm{H}_{3} \mathrm{O}^{+}]$ and $\mathrm{E}=[\mathrm{MnO}_{4}^{2-}, \mathrm{CrO}_{4}^{2-}]$ that do not have similar Lewis dot structure are :

JEE Main · 2026 · 06 Apr 2026 · Shift 1 · Chemical Bonding and Molecular Structure

The pairs among

A = [SO_{3}^{2 -}, CO_{3}^{2 -}]

B = [O_{2}^{2 -}, F_{2}]

C = [CN^{-}, CO]

D = [NH_{3}, H_{3} O^{+}]

and

E = [MnO_{4}^{2 -}, CrO_{4}^{2 -}]

that do not have similar Lewis dot structure are :

Answer: (B)

Two species share a Lewis structure only when they have the same count of valence electrons arranged alike. In

O_{2}^{2 -}

and

F_{2}

(18 valence electrons, one single bond with three lone pairs on each atom), in

C N^{-}

and

CO

(14 electrons, a triple bond with one lone pair on each atom) and in

N H_{3}

and

H_{3} O^{+}

(8 electrons, pyramidal with one lone pair) the partners are isoelectronic and identical. In pair A,

S O_{3}^{2 -}

is pyramidal with a lone pair on sulphur (26 valence electrons) whereas

C O_{3}^{2 -}

is trigonal planar (24 electrons), so they differ. In pair E,

Mn O_{4}^{2 -}

carries an odd

d^{1}

electron while

Cr O_{4}^{2 -}

d^{0}

, so their electron tallies and dot structures are unlike.

The pairs that do not have similar Lewis structures are A and E.

JEE Main · 2026 · 06 Apr 2026 · Shift 1 · Single correct option