Science (086) — AI-generated practice question

Chips manufacturers flush packets with nitrogen gas because nitrogen is an inert gas that does not react with food. Chips are oily/fatty snacks that undergo oxidation (rancidity) in the presence of oxygen, making them stale, foul-smelling, and unfit for eating. Nitrogen displaces oxygen inside the packet, preventing this oxidation reaction.

If packets were sealed with air instead, the oxygen present in air would oxidise the fats/oils in the chips, causing rancidity. The chips would become stale quickly, develop a bad smell and taste, and lose their quality before the expiry date.

Source: Chapter 1, Section 1.2.5 – Oxidation and Reduction

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• The key concept tested here is rancidity, which is oxidation of fats/oils by atmospheric oxygen.
• Nitrogen is chosen because it is inert — it does not react with food.
• The examiner expects two parts: (1) why nitrogen is used (prevents oxidation/rancidity), and (2) what happens with air (oxidation occurs → rancidity). Cover both for full marks.
• The word "rancidity" (or "oxidation of fats") is essential — do not omit it.