Question

The decreasing order of acidity of the following compounds is:

• A. I > II > III
• B. II > I > III
• C. III > II > I
• D. I > III > II

Answer 1

The correct option is B II > I > III


Acidity can be decided by stability of conjugate base.
Most stable the conjugate base, more is the acidity.
Conjugate base of II is aromatic in nature hence most acidic. I has negative charge on the most electronegative carbon of the conjugate base.
III leads to formation of antiaromatic conjugate base hence least stable.