Final answer:
The Lewis dot structure of NH3 (ammonia) shows only one unshared pair of valence electrons.
Step-by-step explanation:
In the Lewis dot structure, the molecule that shows only one unshared pair of valence electrons is NH3 (option c). NH3 has three unpaired valence electrons, and each of these electrons can form a covalent bond by sharing with a hydrogen atom. The Lewis dot structure of NH3 is represented as:
H
|
N
|
H