Explanation

(a)
The acidic strength of the attached group is in the following order :
[image:12_image672.emf]
Note Due to attachment of electron attractive group acidic strength increases and carboxylic acids are more acidic than phenols.
The two moles of $NH_{2}^{-}$ ions will abstract two moles of a most acidic hydrogen out of the four moles of hydrogen present per mole of the given acidic compounds. Hence, after abstraction of two moles of hydrogen and obtained product will be as shown
[image:12_image673.emf]