On placing a piece of zinc metal in a solution of mercuric chloride, it acquires a shining silvery surface but when it is placed in a solution of magnesium sulphate, no change is observed. Give reason.
When piece of zinc metal is placed in a mercuric chloride solution, it displaces mercury from its solution. This is because zinc is more reactive than mercury.
The displaced mercury gives shining silvery surface.
However, when zinc is placed in a solution of magnesium sulphate, no reaction takes place. This is because magnesium is more reactive than zinc.