Final answer:
The amino group (NH₂) is most likely to be responsible for an organic molecule behaving as a base, as it can accept protons, similar to ammonia, and increase the concentration of hydroxide ions in a solution.
Step-by-step explanation:
In organic chemistry, different functional groups confer various properties to molecules, including whether they behave as acids or bases. The group most likely to be responsible for an organic molecule behaving as a base is the amino group (NH₂). This is because amino groups can accept a proton (H+) from water, functioning as a base and forming the OH- ion in the water, similar to how ammonia reacts.
The options given were:
- 1) Carboxyl group
- 2) Amino group
- 3) Hydroxyl group
- 4) Methyl group
Among these, the amino group is the one that can accept protons and increase the concentration of hydroxide ions in a solution, which is a characteristic of a base. While other groups like the carboxyl and hydroxyl groups may appear to be candidates, the carboxyl group actually behaves as an acid, releasing H+ ions, and the hydroxyl group does not typically dissociate to form OH- ions. The methyl group is mainly hydrophobic and has no significant acidic or basic properties.