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NEET CHEMISTRYOrganic Chemistry – Some Basic Principles and Techniques Medium

Question

Which of the following has the minimum bond length?

A

O2−\text{O}_2^-

B

O22−\text{O}_2^{2-}

C

O2\text{O}_2

D

O2+\text{O}_2^+

Step-by-Step Solution

According to Molecular Orbital Theory, bond length decreases as bond order increases . The bond order is calculated as 12(Nb−Na)\frac{1}{2}(N_b - N_a), where NbN_b and NaN_a are the number of bonding and antibonding electrons, respectively. The bond orders for the given oxygen species are:

  • O2\text{O}_2 (16 electrons): Bond order = 10−62=2.0\frac{10 - 6}{2} = 2.0 .
  • O2+\text{O}_2^+ (15 electrons): One electron is removed from the antibonding π∗\pi^* orbital, making the bond order = 10−52=2.5\frac{10 - 5}{2} = 2.5.
  • O2−\text{O}_2^- (17 electrons): One electron is added to the antibonding π∗\pi^* orbital, making the bond order = 10−72=1.5\frac{10 - 7}{2} = 1.5.
  • O22−\text{O}_2^{2-} (18 electrons): Two electrons are added to the antibonding π∗\pi^* orbitals, making the bond order = 10−82=1.0\frac{10 - 8}{2} = 1.0. Since O2+\text{O}_2^+ has the maximum bond order (2.5), it possesses the minimum bond length.

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from Organic Chemistry – Some Basic Principles and Techniques . Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

CHEMISTRYOrganic Chemistry – Some Basic Principles and Techniques followingminimumlength

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