OCR A-Level Chemistry AS Breadth in chemistry (01), June 2024: Question 15

1 mark · Medium difficulty · Multiple Choice

Identify the correct terms to describe the hydrocarbon structure provided among multiple-choice options A, B, C, and D.

Practise this question

Question

Multiple-choice question 15 displaying the skeletal structure of a ring-containing hydrocarbon with two double bonds. Below are four options: A (Alicyclic and saturated), B (Aliphatic and alicyclic), C (Aliphatic and aromatic), and D (Aromatic and unsaturated), along with a box for the answer.
Question text

15 The structure of a hydrocarbon is shown below.

Which terms describe this hydrocarbon?

A Alicyclic and saturated

B Aliphatic and alicyclic

C Aliphatic and aromatic

D Aromatic and unsaturated

Your answer [1]

Mark scheme

Show the mark scheme Mark scheme for question 15 showing the correct answer as B for 1 mark.

15 B 1

How to answer it

Classifying Hydrocarbons: Aliphatic vs Alicyclic vs Aromatic

What this question tests

This question assesses your ability to correctly apply fundamental organic chemistry terminology—specifically distinguishing between aliphatic, alicyclic, aromatic, saturated, and unsaturated hydrocarbon systems based on structural formulas.

Question 15 (Multiple Choice)

Identifying structural descriptors of a cyclic diene

✅ Correct Answer

B (Aliphatic and alicyclic)

Mark Awarded: 1 / 1 mark

💡 Key Knowledge

  • Aliphatic: Carbon atoms joined in unbranched/branched chains, or non-aromatic rings (acyclic or alicyclic).
  • Alicylic: An aliphatic compound arranged in a non-aromatic ring (with or without side chains).
  • Aromatic: Contains a delocalized benzene ring system (arene).
  • Saturated vs Unsaturated: Contains only single C-C bonds (saturated) versus containing double/triple C=C bonds (unsaturated). Note: Option B correctly names the structural frameworks rather than saturation.

🧠 Exam Technique

  • Examine the skeleton: It is a ring structure containing 6 carbon atoms, making it alicyclic.
  • Recall that non-aromatic rings (even with double bonds, like cyclohexadiene) fall under the broader umbrella definition of aliphatic compounds in OCR chemistry.
  • Eliminate options containing "aromatic" (C and D) because there is no benzene ring present.
  • Eliminate option A because "saturated" is incorrect due to the presence of two C=C double bonds.

❌ Common Errors

Many students incorrectly associate "aliphatic" exclusively with open-chain (acyclic) alkanes and alkenes, forgetting that non-aromatic cyclic compounds are classified as alicyclic, which is a sub-category of aliphatic.

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 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.