Science (086) — AI-generated practice question

Copper(II) oxide is reduced in this reaction.

The reaction is:
$$\text{CuO} + \text{H}_2 \xrightarrow{\text{Heat}} \text{Cu} + \text{H}_2\text{O}$$

Reason: A substance is said to be reduced when it loses oxygen during a reaction. In this reaction, copper(II) oxide (CuO) loses its oxygen to hydrogen and is converted to copper (Cu). Therefore, copper(II) oxide is reduced. (Simultaneously, hydrogen gains oxygen and is oxidised, making this a redox reaction.)

Source: Chapter 1, Section 1.2.5 Oxidation and Reduction

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• The examiner expects the term "reduced" clearly stated — this is worth 1 mark.
• The definition (loses oxygen = reduction) must be written — 1 mark.
• Applying the definition to this specific reaction (CuO losing oxygen to become Cu) — 1 mark.
• Mentioning the redox nature or hydrogen's oxidation is a bonus but keep it brief.
• Always write the chemical equation when explaining a reaction; it shows understanding and saves words.