Question

a characterstic change of colour is seen when a piece of ironis added to copper (II) sulphate solution

Answer 1

because the action of iron sulphide make the change colour in the sulphate solution

Answer 2

When an iron nail immersed in the solution of copper sulphate than iron displaces copper from the solution of copper sulphate because iron is more reactive than copper. Therefore copper sulphate solution colour changes from blue to pale green.

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