A student notices that her silver jewellery turned dull and had a grey-black coating over it after wearing for a few months. What results in the change in colour of the silver metal ?
Generated by claude-sonnet-4-6 · 2026-06-14 10:31 · grounding rag
Model Answer
(B) The jewellery comes in contact with air, moisture and acids and corrodes.
Silver reacts with sulphur in air to form a grey-black coating of silver sulphide — this is corrosion, not rusting.
Source: Chapter 1, Section 1.3.1 Corrosion; Chapter 3, Section 3.5 Corrosion
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Explanation
- Option (D) is wrong because rusting is specific to iron; silver does not rust.
- Option (B) is correct: corrosion of silver occurs when it contacts air (containing sulphur), moisture, and acids.
- Examiners expect you to distinguish between rusting (only iron/steel) and corrosion (general term for metals reacting with their environment).
- The textbook specifically states: "Silver articles become black after some time when exposed to air — it reacts with sulphur in the air to form silver sulphide." This is corrosion.