Question

Which of the following compounds contains the -COOH (carboxylic) group?

• A. Acetic acid
• B. Ethanol
• C. Diethyl ether
• D. Formaldehyde

Hint:

The carboxyl group ($-\text{COOH}$) is a combination of a carbonyl group ($>\text{C}=\text{O}$) and a hydroxyl group ($-\text{OH}$) attached to the same carbon atom. Its name "carboxyl" is derived from carbonyl and hydroxyl.

Answer 1

The Correct Option is A

Step 1: Know the group wanted.
We need the compound that carries the carboxyl group, written as $-COOH$.

Step 2: Check each functional group.
Ethanol has $-OH$, an alcohol. Diethyl ether has an $-O-$ bridge. Formaldehyde has $-CHO$, an aldehyde. None of these is a carboxyl group.

Step 3: Look at acetic acid.
Acetic acid is $CH_3COOH$. It clearly carries the $-COOH$ group at the end.

Step 4: Pick the answer.
Only acetic acid has the carboxyl group.
\[ \boxed{\text{Acetic acid}} \]