Q1
1 markVery Short AnswerSection A

Write the name and structure of an aldehyde with four carbon atoms in its molecule.

Carbon and its Compounds
Functional Groups and Nomenclature
Official Answer

The aldehyde containing four carbon atoms is Butanal.


Its molecular formula is C4H8OC_4H_8O (or CH3CH2CH2CHOCH_3CH_2CH_2CHO).


Its structural formula is:


HHHO∣∣∣//H−C−−C−−C−−C∣∣∣\HHHH\begin{array}{ccccc} & H & H & H & O \\ & | & | & | & // \\ H & -C- & -C- & -C- & -C \\ & | & | & | & \backslash \\ & H & H & H & H \end{array}

ButanalCH3CH2CH2CHOaldehyde groupfour carbon atoms

Marking Scheme

  • 1Correct IUPAC name: Butanal (0.5 marks)
  • 2Correct structural formula showing all single bonds and the terminal carbonyl group (0.5 marks)

Hint

An aldehyde has the functional group −CHO-CHO. Count the total number of carbon atoms as four, including the carbon in the functional group, and name it using the suffix '-al'.

Quick Oral Answer

Q: What is the general formula for homologous series of aldehydes? A: The general formula is CnH2nOC_nH_{2n}O (for n≥1n \ge 1) or Cn−1H2n−1CHOC_{n-1}H_{2n-1}CHO.

Analysis & Explanation

An aldehyde group (−CHO-CHO) always contains a carbonyl carbon (C=OC=O) bonded to a hydrogen atom. Since the compound must contain exactly four carbon atoms in total, three carbon atoms form the alkyl chain (propyl group, C3H7−C_3H_7-) and the fourth carbon is part of the aldehyde functional group (−CHO-CHO). According to IUPAC nomenclature, a four-carbon saturated chain with an aldehyde group is named by replacing the '-e' of 'butane' with '-al', giving Butanal.

Common Mistakes

  1. 1Counting the aldehyde carbon separately and drawing a five-carbon chain (pentanal) instead of a four-carbon chain.
  2. 2Forgetting to show the double bond between carbon and oxygen (C=OC=O) in the structural formula.

Interesting Facts

Butanal has an extremely pungent, sweaty, and unpleasant odor at high concentrations, but at very low concentrations, it contributes to the fresh, green aroma of apples and fresh-cut grass.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2016?

This question carries 1 mark in the CBSE Class 10 Science 2016 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Carbon and its Compounds" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Functional Groups and Nomenclature" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2016 paper?

This is a Very Short Answer question from Section A in the CBSE Class 10 Science 2016 paper.