JEE Advanced 2016 · Paper 2 · Chemistry Q25

ChemistryMultiple correct+4 / -2Question 25 of 54

According to Molecular Orbital Theory,

\ce{C2^{2-}}

is expected to be diamagnetic

\ce{O2^{2+}}

is expected to have a longer bond length than

\ce{O2}

\ce{N2+}

and

\ce{N2-}

have the same bond order

\ce{He2+}

has the same energy as two isolated He atoms

Answer and worked solution

Official answer: A, C

(A) $\ce{C2^{2-}}$ has 14 electrons, like N₂: all paired, diamagnetic. True.
(B) $\ce{O2^{2+}}$ has bond order 3 against 2 for O₂, so it has a shorter bond. False.
(C) $\ce{N2+}$ (13 e⁻) and $\ce{N2-}$ (15 e⁻) both have bond order 2.5. True.
(D) $\ce{He2+}$ has bond order ½, so it is lower in energy than two isolated He atoms. False.

(A), (C)

Topics:Molecular orbital theory

JEE Advanced 2016 · Paper 2, Chemistry question 25