question_answer

Correct increasing order of acidity is as follows

A) \[{{H}_{2}}O,{{C}_{2}}{{H}_{2}},{{H}_{2}}C{{O}_{3}}\], phenol

B) \[{{C}_{2}}{{H}_{2}},{{H}_{2}}O,{{H}_{2}}C{{O}_{3}}\], phenol

C) phenol, \[{{C}_{2}}{{H}_{2}},{{H}_{2}}C{{O}_{3}},{{H}_{2}}O\]

D) \[{{C}_{2}}{{H}_{2}},{{H}_{2}}O\], phenol, \[,{{H}_{2}}C{{O}_{3}}\]

Correct Answer: D

Solution :

[d] Such questions can be solved by considering the relative basic character of their conjugated bases which for \[{{H}_{2}}O,{{C}_{2}}{{H}_{2}},{{H}_{2}}C{{O}_{3}}\] and \[{{C}_{6}}{{H}_{5}}OH\] are \[^{-}OH,HC\equiv {{C}^{-}}:,HCO_{3}^{-},{{C}_{6}}{{H}_{5}}{{O}^{-}}\] More the possibility for the dispersal of the negative charge, weaker will be the base. Thus the relative basic character of the four bases is Thus the acidic character of the four  corresponding acids will be \[{{H}_{2}}C{{O}_{3}}>{{C}_{6}}{{H}_{5}}OH>{{H}_{2}}O>HC\equiv CH\]