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Multiple Choice
Which of the following molecules has a carboxyl functional group?
A
R—NH2
B
R—COH
C
R—OPO3–2
D
R—COOH
Verified step by step guidance
1
Understand the structure of a carboxyl functional group. A carboxyl group is characterized by the presence of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (OH). The general formula is R—COOH.
Examine each option to identify the functional groups present. The options given are R—NH2, R—COH, and R—OPO3–2.
Analyze the first option, R—NH2. This represents an amine group, which consists of a nitrogen atom bonded to two hydrogen atoms. It does not contain the carboxyl group structure.
Analyze the second option, R—COH. This represents an aldehyde group, characterized by a carbon atom double-bonded to an oxygen atom and single-bonded to a hydrogen atom. It lacks the hydroxyl group necessary for a carboxyl group.
Analyze the third option, R—OPO3–2. This represents a phosphate group, which includes a phosphorus atom bonded to four oxygen atoms. It does not match the carboxyl group structure. Therefore, the correct molecule with a carboxyl group is R—COOH.