A student in Trinidad investigated the rusting of iron nails. She placed nails in four test tubes under different conditions. In which test tube would the nail rust MOST quickly?

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Question

A student in Trinidad investigated the rusting of iron nails. She placed nails in four test tubes under different conditions. In which test tube would the nail rust MOST quickly?

Accepted Answer

Nail in salt water open to air — Award 1 mark for recognising that rusting requires both oxygen and water, and salt acts as an electrolyte to speed up the oxidation process. A is incorrect — boiled water lacks dissolved oxygen and oil prevents air contact. B is incorrect — dry air lacks the moisture needed for rusting. D is incorrect — a vacuum lacks both oxygen and moisture.

Answer

Nail sealed in a vacuum

Answer

Nail in salt water open to air

Answer

Nail in boiled distilled water covered with oil

Answer

Nail in dry air with calcium chloride drying agent

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