Multiple choice

Red colour of iron turns to brown or yellow when it reacts with oxygen. This red colour of iron turns to greenish or bluish grey by which of the following processes?

  1. Oxidation

  2. Hydration

  3. Carbonation

  4. Reduction

  5. Solution
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When oxidised minerals are placed in an environment where oxygen is absent, reduction takes place. Such conditions exist usually below the water table, in areas of stagnant water and waterlogged ground. Thus, red colour of iron upon reduction turns to greenish or bluish grey.

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