Position Isomerism: This type of isomerism is said to exist in compounds which have the same molecular formula but differ in the position of attachment of a characterstic group or atom. For example, (a)n-propyl chloride and isopropyl chloride both have the same molecular formula C, H, Cl but differ from each other only in the position of attachment of chlorine atom. CH3-CH2-CH2Cl n-propyl chloride CH3-CH-CH3 iso-propyl chloride