To determine the isomerism of a molecule based on its molecular formula and molecular structure, one must first understand the concept of isomers. Isomers are molecules with the same molecular formula but different arrangements of atoms in space. There are two main types of isomerism: structural constitutional isomerism and stereoisomerism.1. Structural constitutional isomerism: This occurs when molecules have the same molecular formula but different connectivity of atoms. To identify structural isomers, compare the connectivity of atoms in the molecular structures.2. Stereoisomerism: This occurs when molecules have the same connectivity of atoms but different spatial arrangements. Stereoisomers can be further divided into two categories: enantiomers and diastereomers. a. Enantiomers: These are non-superimposable mirror images of each other. They have the same connectivity but differ in the arrangement of atoms in space. To identify enantiomers, look for chiral centers carbon atoms with four different substituents and compare the spatial arrangement of the substituents. b. Diastereomers: These are stereoisomers that are not mirror images of each other. They can arise from multiple chiral centers or from restricted rotation around a bond cis-trans isomerism . To identify diastereomers, compare the spatial arrangement of atoms in the molecular structures.Example: C4H10 butane has two isomers:1. n-Butane: The four carbon atoms are connected in a straight chain.2. Isobutane methylpropane : Three carbon atoms are connected in a chain, and the fourth carbon atom is connected to the middle carbon of the chain as a branch.These two isomers are structural isomers because they have the same molecular formula but different connectivity of atoms. They have different properties, such as boiling points: n-butane has a boiling point of -0.5C, while isobutane has a boiling point of -11.7C. This difference in boiling points is due to the difference in their molecular structures, which affects the strength of the intermolecular forces between the molecules.