OCR A-Level Chemistry AS Breadth in chemistry (01), June 2024: Question 18

1 mark · Easy difficulty · Multiple Choice

Identify the functional groups present in the given organic compound containing a carboxylic acid and a ketone.

Practise this question

Question

Multiple choice question 18 asking which functional groups are present in the compound shown. The displayed formula shows a five-carbon chain with a ketone carbonyl group at position 2 and a carboxylic acid group at position 5. Four options are given: A, Alcohol and aldehyde; B, Alcohol and ketone; C, Carboxylic acid and aldehyde; D, Carboxylic acid and ketone.
Question text

18 Which functional groups are present in the compound below?

O

O

OH

A Alcohol and aldehyde.

B Alcohol and ketone.

C Carboxylic acid and aldehyde.

D Carboxylic acid and ketone.

Your answer [1]

Mark scheme

Show the mark scheme The mark scheme indicates the correct answer is D.

18 D 1

How to answer it

Identifying Functional Groups

What this question tests: Recognition and identification of common organic functional groups from displayed/skeletal structural formulas, specifically distinguishing between carbonyl-containing groups (aldehydes, ketones, carboxylic acids) and hydroxyl groups (alcohols).
Question 18 (Multiple Choice)

Core Analysis & Solution

✅ Correct Answer: D

The correct option is D (Carboxylic acid and ketone).

💡 Key Knowledge

  • Carboxylic Acid: Features a carbonyl group ( C=O ) directly attached to a hydroxyl group ( -OH ) at the terminal end of the carbon chain.
  • Ketone: Features a carbonyl group ( C=O ) bonded between two carbon atoms within the carbon chain (not at the terminal end).

🧠 Exam Technique

Scan the molecule systematically from left to right. Locate every oxygen-containing group, check its carbon environment (terminal vs. non-terminal), and match them against the multiple-choice options to eliminate distractors quickly.

❌ Common Errors

  • Mistaking the -OH part of the carboxylic acid group for a separate alcohol functional group.
  • Confusing the internal ketone carbonyl ( C=O ) with an aldehyde (which must be at the end of a chain with a hydrogen attached to the carbonyl carbon).
Mark Scheme Allocation: 1 mark for selecting option D.

Topics

Module 4: Core organic chemistry · Module 6: Organic chemistry and analysis · 4.1 Basic concepts and hydrocarbons · 6.1 Aromatic compounds, carbonyls and acids

Question and mark scheme from the OCR A-Level Chemistry examination, AS Breadth in chemistry (01), June 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.