Enantiomers are a pair of stereoisomers that are non-superimposable mirror images of each other. They have the same molecular formula and the same connectivity of atoms but differ in the arrangement of atoms in three-dimensional space. The presence of a chiral center, usually a carbon atom with four different substituents attached to it, is responsible for the existence of enantiomers in organic chemistry.Optical activity is the ability of a chiral compound to rotate the plane of plane-polarized light when it passes through a solution of the compound. This property is due to the asymmetric arrangement of atoms in chiral molecules, which interact differently with the electric and magnetic components of light. Enantiomers exhibit optical activity, and they rotate the plane of polarized light in opposite directions. One enantiomer will rotate the light clockwise dextrorotatory, denoted as + or d- , while the other enantiomer will rotate it counterclockwise levorotatory, denoted as - or l- .For example, let's consider the chiral molecule 2-butanol:CH3-CH OH -CH2-CH3The chiral center is the second carbon atom, which has four different substituents attached to it: a hydrogen atom, a hydroxyl group, a methyl group, and an ethyl group. There are two enantiomers of 2-butanol:1. R -2-butanol: The enantiomer with the clockwise R configuration around the chiral center.2. S -2-butanol: The enantiomer with the counterclockwise S configuration around the chiral center.These two enantiomers of 2-butanol exhibit optical activity. When plane-polarized light passes through a solution of R -2-butanol, the plane of the light will be rotated in one direction e.g., clockwise , while a solution of S -2-butanol will rotate the plane of the light in the opposite direction e.g., counterclockwise . The specific rotation values for each enantiomer will be equal in magnitude but opposite in sign.In summary, the relationship between enantiomers and optical activity in organic chemistry is that enantiomers are chiral molecules that can rotate the plane of plane-polarized light due to their asymmetric arrangement of atoms. Each enantiomer will rotate the light in opposite directions, and this property can be used to distinguish between enantiomers and determine the enantiomeric purity of a sample.