Science (086) — AI-generated practice question

Observation: When dilute HCl solution is tested, the bulb glows, indicating it conducts electricity. When glucose solution is tested, the bulb does not glow, showing glucose solution does not conduct electricity.

Reason: HCl ionises in water to produce H⁺(aq) and Cl⁻ ions. These ions carry electric current through the solution. Glucose, despite containing hydrogen, does not ionise in water and produces no ions.

Conclusion: The presence of hydrogen alone does not make a substance acidic. A substance is acidic only if it produces H⁺(aq) ions (hydronium ions, H₃O⁺) in aqueous solution. This is what makes HCl an acid while glucose is not.

Source: Chapter 2, Section 2.2 (Activity 2.8)

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• Examiners expect: the specific observation (bulb glows / does not glow), the reason (ions / no ions), and the conclusion about what makes a substance acidic.
• Key phrase to use: "ionisation" and "H⁺(aq) ions in solution."
• Don't just say "HCl is an acid" — explain why in terms of ion production.
• This question tests Activity 2.8 directly; the three-part structure (observation → reason → conclusion) is the ideal format for 3 marks.