OCR A-Level Chemistry AS Breadth in chemistry (01), June 2019: Question 15

1 mark · Medium difficulty · Multiple Choice

Identify which compound is unsaturated, alicyclic and contains an alkyl group from the given options.

Practise this question

Question

Multiple choice question 15 asking which compound is unsaturated, alicyclic and contains an alkyl group, with four options A, B, C, and D shown as chemical structures. Option A shows methylbenzene (toluene), option B shows methylcyclobutane, option C shows 1-methylcyclopentene, and option D shows methylenecyclohexane.
Question text

15 Which compound is unsaturated, alicyclic and contains an alkyl group?

A

B

C

D

Your answer [1]

Mark scheme

Show the mark scheme Mark scheme showing that the correct answer for question 15 is C.

15 C 1 AO1.2

How to answer it

Organic Terminology and Structural Identification

What this question tests

This question assesses your ability to recall and apply key organic chemistry definitions, specifically differentiating between aliphatic, alicyclic, aromatic, saturated, and unsaturated systems, alongside recognizing functional groups like alkyl groups within skeletal formulae.

Question 15 Analysis

Core Answer & Breakdown

✅ Correct Answer: C

Compound C contains a non-aromatic ring (alicyclic), a carbon-carbon double bond (unsaturated), and a methyl branch attached directly to the ring (an alkyl group).

💡 Key Knowledge Definitions

  • Unsaturated: Contains at least one double (or triple) bond between carbon atoms.
  • Alicyclic: Arranged in a non-aromatic ring structure (can be saturated or unsaturated).
  • Alkyl group: A side-chain functional group with the general formula CnH₂n₊₁ (e.g., methyl, ethyl).

🧠 Exam Technique

Process of elimination is your best tool for multiple-choice structural questions. Check each criterion one by one against all options before making your final selection.

❌ Common Errors

  • Confusing alicyclic with aromatic (e.g., choosing Option A, which contains a benzene ring).
  • Overlooking whether a compound is fully saturated or has a double bond hidden in the ring structure.

Detailed Option Breakdown

  • A: Contains a benzene ring, making it aromatic rather than alicyclic. Incorrect.
  • B: Alicyclic ring with an alkyl group, but it contains only single bonds (fully saturated). Incorrect.
  • C: A 5-membered non-aromatic ring (alicyclic), features a C=C double bond (unsaturated), and has a methyl side-chain (alkyl group). Correct!
  • D: Alicyclic ring with an exocyclic double bond, but the double bond is directly attached to the ring carbon via a =CH₂ group, lacking a separate standalone alkyl side-chain branch in the context of the structural options provided.
Marks available: [1 mark] • Assessment Objective: AO1.2 (Demonstrate knowledge and understanding of scientific ideas)

Topics

Module 4: Core organic chemistry · 4.1 Basic concepts and hydrocarbons

Question and mark scheme from the OCR A-Level Chemistry examination, AS Breadth in chemistry (01), June 2019. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.