Chemistry Chemical Bonding ETEA 2024
PMDC Verified Question 11 of 102
The unhybridized p orbital in \( \text{sp}^2 \) hybridization is:
A
In the same plane
B
Out of the plane
C
Parallel to \( \text{sp}^2 \) orbitals
D
Perpendicular to \( \text{sp}^2 \) orbitals
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Perpendicular to \( \text{sp}^2 \) orbitals
Concept:

In \( \text{sp}^2 \) hybridization, three hybrid orbitals form a flat geometric plane to form sigma bonds, while the remaining unhybridized p-orbital is reserved for forming pi bonds.

Formula:

$$ \text{sp}^2 \text{ Plane (XY)} \perp \text{p}_z \text{ orbital (Z)} $$

Solution:

  • The three \( \text{sp}^2 \) hybrid orbitals arrange themselves at 120° angles in a flat plane (e.g., the XY plane) to minimize repulsion.


  • The one remaining unhybridized p-orbital (e.g., \( \text{p}_z \)) stands straight up and down, piercing directly through the center of this plane.


  • Therefore, it is strictly perpendicular (90°) to the plane of the hybrid orbitals.


Why other options are incorrect:

  • Option A, Option B, Option C: If the p-orbital were in the same plane or parallel, it could not form the sideways overlap necessary for a pi-bond without catastrophic spatial interference with the sigma bonds.

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