​Select the functional group in five-carbon atom compound 'Pentanal'.​

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Correct option is B

The correct answer is (b) Aldehyde​

Explanation: The functional group in pentanal is the aldehyde group.

Key features of pentanal:

• It has five carbon atoms in total (hence the "pent" in its name).
• The aldehyde group is at the end of the carbon chain, which is characteristic of aldehydes.
• Therefore, pentanal (C₅H₁₀O) belongs to the aldehyde family, with the aldehyde functional group (-CHO) present at the terminal carbon atom of the five-carbon chain.​