The number of molecules or ions from the following, which do not have odd number of electrons are ______. (A) $\mathrm{NO}_{2}$ (B) $\mathrm{ICl}_{4}^{-}$ (C) $\mathrm{BrF}_{3}$ (D) $\mathrm{ClO}_{2}$ (E) $\mathrm{NO}_{2}^{+}$ (F) NO

JEE Main · 2023 · 29 Jan 2023 · Shift 1 · Chemical Bonding and Molecular Structure

The number of molecules or ions from the following, which do not have odd number of electrons are ______.
(A)

NO_{2}

(B)

ICl_{4}^{-}

(C)

BrF_{3}

(D)

ClO_{2}

(E)

NO_{2}^{+}

(F) NO

Answer: 3

Counting the total electrons in each species tells which carry an unpaired odd electron.

N O_{2}

has 23,

Cl O_{2}

has 33 and

NO

has 15, each an odd total and so an odd-electron species. The tetrachloroiodate ion

IC l_{4}^{-}

has 122, bromine trifluoride

Br F_{3}

has 62 and the nitronium ion

N O_{2}^{+}

has 18, each an even total with all electrons paired. The number of species that do not have an odd electron count is three.

JEE Main · 2023 · 29 Jan 2023 · Shift 1 · Integer answer