Give reason for the following:
a) Metals are regarded as electropositive elements.
b) When a piece of copper metal is added to a solution of Zinc sulphate, no change take place, but the blue colour of copper sulphate fades away when a piece of zinc is placed in its solution .
c) Articles of aluminium do not corrode even though alluminium is an active metal.

Explanation

a) Metals have a tendency to lose one or more electrons to form positive ions. Therefore, metals are called electropositive elements.
Copper is less reactive than Zinc. Therefore, if cannot displace Zinc from `ZnSO_4` solution. But Zinc being more reactive than copper, it displaces copper from `CuSO_4` solution. As a result the concentration of `Cu^(2+)` ions fall and blue colour fades.
` Zn(s) + underset("blue")(CuSO_4(aq) )to underset("colourless")(ZnSO_4 (aq) ) + Cu(s)`
c) Aluminium being a reactive metal readily combines with oxygen to give a protective layer of `AI_2O_3` . As a result further corrosion stops.