Four compounds are shown. These compounds react more quickly, or they react with more favorable equilibrium constants, than similar compounds with less conjugated systems. In each case, explain the enhanced reactivity.
Here we have to compare the reactivity of both the compounds.
Here H-A is the general form of an acid. In between this two resonance structures, the 1st resonance structure is aromatic and the second one is nonaromatic .Thus the 1st compound is more stable than the 2nd one because in the 2nd structure the protonation has been carried out on a singly bonded oxygen atom and generate an unstable product whereas in the 1st compound the cation produced is aromatic and resonance stabilized. Thus the 1st compound is more basic than the the second compound.
Here both the structures are resonance stabilized, but the 1st compound is aromatic whereas the 2nd compound is aliphatic. An aromatic compound is more stable than that of an aliphatic compound. It is known that the reaction that produces more stable product will usually carried out faster under mild condition and having lower activation energy. Thus the 1st compound ionizes more readily than that of the second compound.