There are two main types of isomers: geometric isomers and structural isomers.1. Geometric isomers: These isomers have the same molecular formula and the same structural formula, but they differ in the spatial arrangement of their atoms or groups. Geometric isomerism occurs when there is restricted rotation around a bond, such as a double bond or a ring structure. Geometric isomers can be classified into two types: cis-isomers and trans-isomers.To determine if a molecule exhibits geometric isomerism, look for the presence of a double bond or a ring structure with different groups attached to the carbon atoms involved in the restricted rotation.Example: Cis-2-butene and trans-2-butene are geometric isomers. Both have the molecular formula C4H8, but in cis-2-butene, the two methyl groups are on the same side of the double bond, while in trans-2-butene, they are on opposite sides. These isomers have different physical properties, such as boiling points and melting points. Cis-isomers generally have higher boiling points due to stronger intermolecular forces, while trans-isomers have lower boiling points.2. Structural isomers: These isomers have the same molecular formula but different structural formulas. They are connected in a different order, resulting in different chemical and physical properties. Structural isomerism can be further classified into several types, including chain isomerism, position isomerism, and functional group isomerism.To determine if a molecule exhibits structural isomerism, compare the structural formulas of the molecules with the same molecular formula. If the connectivity of the atoms is different, they are structural isomers.Example: Pentane C5H12 and 2-methylbutane C5H12 are structural isomers. Both have the same molecular formula, but pentane has a straight chain of five carbon atoms, while 2-methylbutane has a branched chain with four carbon atoms in the main chain and one methyl group attached to the second carbon atom. These isomers have different physical properties, such as boiling points and melting points. Branched-chain isomers generally have lower boiling points due to weaker intermolecular forces, while straight-chain isomers have higher boiling points.