Social Science (087) — AI-generated practice question

Placer deposits are alluvial deposits found in the sands of valley floors and the base of hills, formed by the accumulation of minerals carried by water.

Minerals found in placer deposits are resistant to weathering because they are not corroded by water. Being chemically stable, they survive the action of water and remain concentrated in these deposits.

Two examples: Gold and Platinum (also tin and silver).

Source: Chapter 5 – Resources and Development, Mode of Occurrence of Minerals

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• The definition must mention "alluvial deposits" and "valley floors/base of hills" — these are the key textbook phrases.
• The reason asked is not corroded by water — state this directly; don't over-explain.
• For examples, any two from: gold, silver, tin, platinum — all four are listed in the textbook, pick two.
• This is a 3-mark question: definition (1), reason (1), two examples (1). Keep it compact.