AQA A-Level Chemistry Paper 3, 2023: Question 14

1 mark · Easy difficulty · Multiple Choice

Oxide with Highest Oxidation State This question asks you to determine which oxide contains the named element in its highest possible oxidation state, assessing your understanding of oxidation numbers and chemical compounds.

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Question

AQA A-Level Chemistry Paper 3, 2023: Question 14
Question text

14 In which oxide is the named element in its highest oxidation state?

[1 mark]

A chlorine in ClO2

B magnesium in MgO

C nitrogen in N2O4

D sulfur in SO2

Mark scheme

Show the mark scheme Mark scheme for AQA A-Level Chemistry Paper 3, 2023: Question 14

14 B 1 (AO1) magnesium in MgO

How to answer it

Understanding Oxidation States in Oxides

Question

In which oxide is the named element in its highest oxidation state?

  • A: Chlorine in ClO2
  • B: Magnesium in MgO
  • C: Nitrogen in N2O4
  • D: Sulfur in SO2

Correct Answer: B

The correct answer is B: Magnesium in MgO . Magnesium in MgO has an oxidation state of +2, which is its highest possible oxidation state. This corresponds to its loss of both valence electrons.

Teacher Tip: Always consider the highest number of valence electrons that an element can lose or gain when determining its highest oxidation state.

Explanation of Other Options

  • A: Chlorine in ClO2 has an oxidation state of +4. However, chlorine can achieve a higher oxidation state of +7 in compounds like ClO4-.
  • C: Nitrogen in N2O4 has an oxidation state of +4. Its highest oxidation state is +5, as seen in compounds like HNO3.
  • D: Sulfur in SO2 has an oxidation state of +4. Its highest oxidation state is +6, as seen in SO3.

Key Takeaways

The highest oxidation state of an element corresponds to the maximum number of valence electrons it can lose, gain, or share. In this case, magnesium achieves its highest state of +2 in MgO.

Final Answer

The correct answer is:

B: Magnesium in MgO

Topics

Physical Chemistry · 3.1.7 Oxidation, Reduction, and Redox Equations

Question and mark scheme from the AQA A-Level Chemistry examination, Paper 3, 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.