Which functional group is responsible for the acidic properties of vinegar?

• A. Aldehyde group ($CHO$)
• B. Carboxyl group ($COOH$)
• C. Hydroxyl group ($OH$)
• D. Amino group ($N{H}_2$)

Answer: (B)

Verified step by step guidance

1. Identify the main components of vinegar, which is primarily a dilute solution of acetic acid.
2. Recall that acetic acid contains the carboxyl functional group, which is written as \(\mathrm{\text{–COOH}}\).
3. Understand that the acidic property of vinegar comes from the ability of the carboxyl group to donate a proton (H\(^+\)) to the solution.
4. Compare the functional groups listed: aldehyde (\(\mathrm{\text{–CHO}}\)), carboxyl (\(\mathrm{\text{–COOH}}\)), hydroxyl (\(\mathrm{\text{–OH}}\)), and amino (\(\mathrm{\text{–NH_2}}\)), and recognize that only the carboxyl group is acidic.
5. Conclude that the carboxyl group is responsible for the acidic properties of vinegar because it can release H\(^+\) ions, lowering the pH.