Final answer:
The most reasonable Lewis structure for a molecule with N, C, and H atoms is ammonia (NH3), where nitrogen has three bonds with hydrogen and one lone pair, following the octet rule and exhibiting a trigonal pyramidal geometry.
Step-by-step explanation:
The most reasonable Lewis structure for a molecule that contains an N (nitrogen) atom, a C (carbon) atom, and an H (hydrogen) atom, is the Lewis structure of ammonia, NH3. In this structure, the nitrogen atom is the central atom and it has five valence electrons while each hydrogen atom contributes one valence electron. This results in the electron structure NH3 where nitrogen has three bonding pairs of electrons with the hydrogen atoms and one lone pair of electrons.
This structure is supported by the facts that nitrogen typically forms three bonds, obeys the octet rule, and exhibits a tetrahedral geometry to minimize repulsions between the electron pairs according to VSEPR theory.
This makes NH3 a AX3E molecule, indicating it has three bonding pairs and one lone pair. The lone pair of electrons on nitrogen result in a trigonal pyramidal molecular geometry.