Question: Rank the compounds in each group in order of increasing acidity. Rank the compounds in each group in order of increasing acidity.

a.

b.

Carboxylic acids comprising electron-withdrawing groups are stable than those having electron-donating groups. The conjugate base is destabilized when electron-donating groups are present.

The acid comprising several electronegative substituents is more acidic than those acids which do not possess electronegative substituents. Higher the electronegativity of the substituent, more acidic is the particular compound

The third compound, among the other compounds, is more acidic because of the presence of two OH groups. The first compound is least acidic because of the presence of the methyl group that is least electronegative.

The acidity order can be given as:

Acidity of the different compounds in question a

b. Electronegativity of iodine is greater than that of carbon atom. The presence of one extra ${\mathrm{CH}}_2$ group in the third compound of the given compounds in question b makes it less acidic than the first compound.

Hence the acidic order can be given as:

Acidity of the different compounds in question b