Which of the indicated hydrogen in the following compounds is the most acidic?

Question

Quizplus · Accepted Answer

The acidity of a hydrogen atom is dependent on its ability to be removed as a proton. In compound III, the hydrogen on the -NH group is the most acidic because it forms a stable conjugate base (ammonia) through the donation of the lone pair of electrons on the nitrogen. The hydrogen attached to the alkyl group in I and II are less acidic due to the electron-donating nature of the neighboring carbon atoms. The hydrogen attached to the aromatic ring in IV is also less acidic due to the stabilization of the conjugate base by resonance.

Which of the Indicated Hydrogen in the Following Compounds Is