Chemistry Chemical Bonding ETEA 2022
PMDC Verified Question 45 of 102
The shape of ammonia (\( \text{NH}_3 \)) is
A
Trigonal bi pyramidal
B
Trigonal pyramidal
C
Trigonal planner
D
Square planner
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Trigonal pyramidal
Concept:

The molecular shape is determined by the positions of the atoms, heavily influenced by the lone pairs on the central atom (VSEPR theory).

Formula:

$$ \text{Type} = \text{AB}_3\text{E} $$

Solution:

  • Ammonia has a central Nitrogen atom bonded to 3 Hydrogen atoms, leaving 1 lone pair.


  • The 4 total electron domains arrange themselves in a tetrahedral geometry to minimize repulsion.


  • Because one of those domains is an invisible lone pair, the observable shape formed by the atoms is a trigonal pyramid.


Why other options are incorrect:

  • Option A: Requires 5 bond pairs (e.g., \( \text{PCl}_5 \)).
  • Option C: Requires 3 bond pairs and 0 lone pairs.
  • Option D: Requires 4 bond pairs and 2 lone pairs.

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