Ans. Molecules that have the same molecular formula but a completely different arrangement of the atoms in space then they are called isomers. Therefore, isomers can have the same molecular formula but the physical properties of each molecule might differ, especially in the case where the functional groups are different. The phenomenon in which one compound has the same chemical formula but a different chemical structure is called isomerism.Furthermore, there are three common types of isomers that are isomers of the chain, isomers of the functional group, and positional isomers. In the case of chain isomers, the molecular formula is the same but has different arrangements or divisions. In the can of functional group isomers, the formula is the same but the functional group is completely different.