An organic compound with general formula RCOR' is an

Step 1: Analyze the question We need to identify the homologous series from the general formula RCOR'. Here R and R' are both alkyl groups (or hydrocarbon groups) attached to a carbonyl carbon (C=O).

Step 2: Recall the functional groups

| Class | General formula | Functional group | |---|---|---| | Alkanal (aldehyde) | RCHO | carbonyl with one H attached | | Alkanone (ketone) | RCOR' | carbonyl between two carbon groups | | Alkanoic acid | RCOOH | carboxyl group | | Alkanoate (ester) | RCOOR' | carboxyl with an alkyl group in place of H |

Step 3: Match the formula RCOR' has a carbonyl group (C=O) bonded to two hydrocarbon groups, R and R'. That is the structure of a ketone, named alkanone in IUPAC nomenclature.

• It is not an alkanal, because an aldehyde has at least one H on the carbonyl carbon (RCHO).
• It is not an alkanoate, because an ester has an extra oxygen (RCOOR').
• It is not an alkanoic acid, because an acid has the -COOH group.

Example: CH₃COCH₃ is propanone (acetone), the simplest ketone.

Answer: A. alkanone

Exam tip: Look at what is attached to the C=O.

• H and R gives aldehyde (alkanal).
• R and R' gives ketone (alkanone).
• OH gives acid.
• OR' gives ester (alkanoate).

Notice that the "COO" in an ester formula has two oxygens. RCOR' has only one oxygen, so it must be a ketone.