Select the best word or phrase that completes each sentence…

Select the best word or phrase that completes each sentence (alkynes, enol, keto, with, without, aldehydes, tautomers, acetylide, ionic, resonance, higher, lower, decreases, increases,  rotation, alkenes, ketones, carboxylic acids, nitrogen, bromine, chlorine, oxygen, cis, trans, anti, dihydroxylation, epoxidation, oxidative, reduction, syn, alkylation, odd, even, hydroboration, regioselective, above , below, allylic)   …………………..  are constitutional isomers that differ in the location of a double bond and a hydrogen and exist in an equilibrium with each other. Complete word/phrase and correct spelling (verbatim) is required. No partial credit.