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NEET CHEMISTRYOrganic Chemistry – Some Basic Principles and Techniques Easy

Question

Which one of the following molecules is paramagnetic?

A

H2_2

B

Li2_2

C

C2_2

D

O2_2

Step-by-Step Solution

  1. Definition: According to Molecular Orbital Theory, a molecule is paramagnetic if it contains unpaired electrons in its molecular orbitals .
  2. Analyze H2_2: Configuration is σ1s2\sigma_{1s}^2. All electrons are paired. It is diamagnetic .
  3. Analyze Li2_2: Configuration involves filled σ1s,σ1s∗,σ2s\sigma_{1s}, \sigma^*_{1s}, \sigma_{2s} orbitals. All electrons are paired. It is diamagnetic .
  4. Analyze C2_2: Configuration ends with π2px2π2py2\pi_{2p_x}^2 \pi_{2p_y}^2. All electrons are paired. It is diamagnetic .
  5. Analyze O2_2: The electronic configuration is \sigma_{1s}^2 \sigma^*_{1s}^2 \sigma_{2s}^2 \sigma^*_{2s}^2 \sigma_{2p_z}^2 (\pi_{2p_x}^2 = \pi_{2p_y}^2) (\pi^*_{2p_x}^1 = \pi^*_{2p_y}^1). It contains two unpaired electrons in the antibonding π∗\pi^* orbitals. Therefore, O2_2 is paramagnetic .

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.

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A.$\text{BCl}_3$ and $\text{BrCl}_3$
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