1. cis-2-butene and trans-2-butene: These two molecules exhibit stereoisomerism, specifically geometric isomerism also known as cis-trans isomerism or E/Z isomerism . They have the same molecular formula and connectivity, but differ in the spatial arrangement of their atoms around the double bond.2. Butan-2-ol and 2-methylpropan-2-ol: These two molecules exhibit structural isomerism also known as constitutional isomerism . They have the same molecular formula, but the atoms are connected differently, resulting in different functional groups and properties.3. 2-chloropropane and 1-chloropropane: These two molecules also exhibit structural isomerism. They have the same molecular formula, but the chlorine atom is connected to different carbon atoms in each molecule, resulting in different properties.4. Methoxyethane and ethanol: These two molecules exhibit structural isomerism as well. They have the same molecular formula, but the atoms are connected differently, resulting in different functional groups an ether in methoxyethane and an alcohol in ethanol and properties.