Which of these compounds has chemical properties most similar to the chemical properties of ethanoic acid? (1) c3h7cooh (3) c2h5cooc2h5(2) c2h5oh (4) c2h5oc2h5

You need to first consider the properties of ethanoic acid that are worth noting. Ethanoic acid is a weak acid (the carboxyl group has a resonance-stabilized base), and the length of its carbon chain (2 carbons) reflects the strength of its Van der Waals forces. Also, the hydroxyl group (as part of the carboxyl group) confers a large dipole moment to the compound. The most similar compound would be the one that resembles ethanoic acid in these respects. Thus, I would say that the answer is (2) C2H5OH. Because oxygen is highly electronegative, it can retain an extra electron without much difficulty, making the hydroxyl group slightly acidic. The hydroxyl group also confers a large dipole moment, and the 2 carbon backbone indicates similar Van der Waals interactions.

They are all full and don't need any more electrons in there outer shell.