JEE Main · 2021 · 18 Mar 2021 · Shift 1 · Chemical Bonding and Molecular Structure

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AX is a covalent diatomic molecule where A and X are second row elements of periodic table. Based on molecular orbital theory, the bond order of AX is 2.5. The total number of electrons in AX is ______. (Round off to the nearest integer).

Answer: 15

Solution

A bond order of

2.5

needs the bonding electrons to exceed the antibonding ones by five. Filling the second-row diatomic scheme in the order that applies when the

σ_{2 p}

level lies below the

π_{2 p}

pair gives

σ_{1 s}^{2} σ_{1 s}^{* 2} σ_{2 s}^{2} σ_{2 s}^{* 2} σ_{2 p_{z}}^{2} π_{2 p_{x}}^{2} π_{2 p_{y}}^{2} π_{2 p_{x}}^{* 1}

which holds

15

electrons, ten bonding and five antibonding, so the bond order is

\frac{10 - 5}{2} = 2.5

. The heteronuclear diatomic with this count is nitric oxide, and the total number of electrons in AX is 15.

JEE Main · 2021 · 18 Mar 2021 · Shift 1 · Integer answer

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JEE Main · 2021 · 18 Mar 2021 · Shift 1 · Chemical Bonding and Molecular Structure

Solution

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