Final answer:
The molecules shown in (a) and (b) are similar in that they both consist of two atoms connected by a chemical bond, but differ in the identity of the atoms involved. This relationship between molecules is called molecular bonding.
Step-by-step explanation:
The molecules shown in (a) and (b) are similar in that they both consist of two atoms connected by a line, which represents a chemical bond. However, they differ in the identity of the atoms involved. The molecule in (a) consists of a carbon atom (labeled "C 1") bonded to a hydrogen atom (labeled "H"), while the molecule in (b) consists of a hydrogen atom bonded to another hydrogen atom. The type of relationship between these molecules is called "molecular bonding."