The pK_a values for the following compounds

are in the order

Concept:

• The acidic strength of an acid depends upon the stability of the conjugate base formed in the hydrolysis of the acid.
• The negative logarithmic of Ka is denoted by pKa.
• The pKa value determines whether an acid is strong or weak.
• The dissociation of acid in an aqueous solution is indicated by pKa.
• If an acid’s pKa is high, it is a weak acid, and if it is low, it is a strong acid.
• The concentration of acid, conjugate base, and H+ affects the pKa.
• Carbolic acid is the weakest acid among the options given above, so it will have the maximum pKa value.
• Thus, the pKa value is inversely proportional to the acidic strength of an acid. Hence the weakest acid will have the highest pKa value which is phenol in this case.
• In A active methelin compound has hyperconjugation
• In B active methelin compound has +M.
• Cyclic methelin compounds are more acidic than acyclic compounds.
• So the order of acidity is A > C > B
• the Pka order will be reversed of it
• B > C > A

So the correct order is B > C > A

NOTE:-The answer provided was according to question and statement, but according to official answer key answer is option 3