OCR A-Level Chemistry Synthesis and analytical techniques (02), June 2022: Question 14

1 mark · Medium difficulty · Multiple Choice

Identify which of the given species (NH3, OH-, CH3NH2) can act as a nucleophile.

Practise this question

Question

Multiple choice question 14 asks which species could react as a nucleophile, listing 1: NH3, 2: OH-, and 3: CH3NH2. Four options are provided: A (1, 2 and 3), B (Only 1 and 2), C (Only 2 and 3), and D (Only 1), with a box for the answer.
Question text

14 Which species could react as a nucleophile?

1 NH3

2 OH–

3 CH3NH2

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Your answer

[1]

Mark scheme

Show the mark scheme The mark scheme indicates that the correct answer for question 14 is option A.

14 A 1 AO1.1

How to answer it

Identifying Nucleophiles

What this question tests

This question assesses your core understanding of organic reaction mechanisms (specifically nucleophilic substitution and addition), testing your ability to recognize structural features that define a nucleophile—namely, a lone pair of electrons capable of being donated to an electron-deficient carbon atom.

Question 14 Multiple Choice Analysis

Core Concepts & Breakdown

✅ Correct Answer: A (1, 2 and 3)

All three listed species possess a lone pair of electrons and can act as nucleophiles in chemical reactions.

💡 Key Knowledge

A nucleophile is an electron-pair donor. To act as a nucleophile, a species must have:

  • A lone pair of electrons
  • (Often) A negative or partial negative charge that increases electron density

🧠 Exam Technique

Evaluate each statement systematically rather than guessing:

  • Statement 1 (NH₃): Nitrogen has 5 outer shell electrons, forming 3 bonds with H, leaving 1 lone pair. Correct.
  • Statement 2 (OH⁻): Oxygen has a negative charge and 3 lone pairs. Strongly nucleophilic. Correct.
  • Statement 3 (CH₃NH₂): Primary amine containing a nitrogen atom with a lone pair (similar to ammonia). Correct.

❌ Common Errors

Students frequently forget that neutral molecules like ammonia ( NH₃ ) and primary amines ( CH₃NH₂ ) can be nucleophiles because they fixate purely on negative ions like hydroxide ( OH⁻ ). Remember: a negative charge is not strictly required, just a lone pair!

Mark Scheme Allocation: 1 mark available for selecting option A (AO1.1: Demonstrate knowledge and understanding of scientific ideas).

Topics

Module 4: Core organic chemistry · Module 6: Organic chemistry and analysis · 4.1 Basic concepts and hydrocarbons · 4.2 Alcohols, haloalkanes and analysis · 6.2 Nitrogen compounds, polymers and synthesis

Question and mark scheme from the OCR A-Level Chemistry examination, Synthesis and analytical techniques (02), June 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.