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NEET CHEMISTRYOrganic Chemistry – Some Basic Principles and Techniques Medium

Question

The correct order of energies of molecular orbitals of N2_2 molecule is:

A

σ1s<σ∗1s<σ2s<σ∗2s<(π2px=π2py)<σ2pz<(π∗2px=π∗2py)<σ∗2pz\sigma 1s < \sigma^* 1s < \sigma 2s < \sigma^* 2s < (\pi 2p_x = \pi 2p_y) < \sigma 2p_z < (\pi^* 2p_x = \pi^* 2p_y) < \sigma^* 2p_z

B

σ1s<σ∗1s<σ2s<σ∗2s<σ2pz<(π2px=π2py)<(π∗2px=π∗2py)<σ∗2pz\sigma 1s < \sigma^* 1s < \sigma 2s < \sigma^* 2s < \sigma 2p_z < (\pi 2p_x = \pi 2p_y) < (\pi^* 2p_x = \pi^* 2p_y) < \sigma^* 2p_z

C

σ1s<σ∗1s<σ2s<σ∗2s<σ2pz<(π2px=π2py)<(π∗2px=π∗2py)<σ∗2pz\sigma 1s < \sigma^* 1s < \sigma 2s < \sigma^* 2s < \sigma 2p_z < (\pi 2p_x = \pi 2p_y) < (\pi^* 2p_x = \pi^* 2p_y) < \sigma^* 2p_z

D

σ1s<σ∗1s<σ2s<σ∗2s<σ2pz<(π2px=π2py)<σ∗2pz<(π∗2px=π∗2py)\sigma 1s < \sigma^* 1s < \sigma 2s < \sigma^* 2s < \sigma 2p_z < (\pi 2p_x = \pi 2p_y) < \sigma^* 2p_z < (\pi^* 2p_x = \pi^* 2p_y)

Step-by-Step Solution

  1. General Rule: For homonuclear diatomic molecules of the second period, the order of molecular orbital energies depends on the number of electrons.
  2. Molecules with Z > 7 (O2{_2}, F2{_2}, Ne2{_2}): The energy of the σ2pz\sigma 2p_z orbital is lower than that of the π2px\pi 2p_x and π2py\pi 2p_y orbitals .
  3. Molecules with Z ≤\le 7 (Li2{_2}, Be2{_2}, B2{_2}, C2{_2}, N2{_2}): Experimental observations show a different order due to the mixing of 2s and 2p orbitals (s-p mixing). In these cases, the energy of the σ2pz\sigma 2p_z orbital is higher than that of the π2px\pi 2p_x and π2py\pi 2p_y orbitals .
  4. Specific Order for N2{_2}: The increasing order of energies is: σ1s<σ∗1s<σ2s<σ∗2s<(π2px=π2py)<σ2pz<(π∗2px=π∗2py)<σ∗2pz\sigma 1s < \sigma^* 1s < \sigma 2s < \sigma^* 2s < (\pi 2p_x = \pi 2p_y) < \sigma 2p_z < (\pi^* 2p_x = \pi^* 2p_y) < \sigma^* 2p_z This corresponds to Option A.

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 correctenergiesmolecularorbitalsmolecule

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