Bronsted Lowry Acids And Bases

Common upon H_(2)O as an Arrhenius acid/base ,Bronsted-Lowry acid/base and Lewis acid /base.

Treatment of indene with NaNH_(2) forms its conjugate base in a Bronsted-Lowry acid-base reaction. Draw all reasonable resonance structures for indene's conjugate base and explain why the pK_(a) of indene is lower than the pK_(a) of most hydrocarbons.

Species acting both as Bronsted acid and base is

Species acting as both Bronsted acid and base is: