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AIIMS 2005
Exam
AIIMS
Year
2005
Subject
Chemistry
Chapter
Chemical Bonding and Molecular Structure

AIIMS 2005 · Chemistry · Chemical Bonding and Molecular Structure

Assertion : B_2 molecule is diamagnetic. Reason : The highest...

Assertion : B2\mathrm{B}_2 molecule is diamagnetic. Reason : The highest occupied molecular orbital is of σ\sigma type.

Options

  1. AIf both assertion and reason are true and reason is the correct explanation of assertion
  2. BIf both assertion and reason are true but reason is not the correct explanation of assertion
  3. CIf assertion is true but reason is false
  4. DIf both assertion and reason are false.

Correct answer

D. If both assertion and reason are false.

Step-by-step solution

In B2\mathrm{B}_2, total number of electrons =10=10 B2→σ(1s)2σ∗(1s2)σ(2s)2σ∗(2s)2σ(2px)1π(2py)1\mathrm{B}_2 \rightarrow \sigma(1 s)^2 \sigma^*\left(1 s^2\right) \sigma(2 s)^2 \sigma^*(2 s)^2 \sigma\left(2 p_x\right)^1 \pi\left(2 p_y\right)^1 Presence of unpaired electron shows the paramagnetic nature. The highest occupied molecular orbital is of π\pi-type.
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