Concept:The shape of a molecule is determined by the Valence Shell Electron Pair Repulsion (VSEPR) theory, which considers both bonding pairs and lone pairs around the central atom.
Explanation:In ammonia,
NH3, nitrogen is the central atom and has five valence electrons.
Three of these electrons form single bonds with three hydrogen atoms.
The remaining two electrons exist as a lone pair on nitrogen.
Lone pairs repel more strongly than bonding pairs.
This lone pair pushes the three
N−H bonds slightly closer together.
As a result, the molecule is not a perfect tetrahedron.
The actual shape of
NH3 is therefore described as trigonal pyramidal.
Among the given options, this is best represented by the term "trigonal".
Answer:D. trigonal