(a) When zinc pieces are added to hydrochloric acid, zinc displaces hydrogen. As a result, zinc chloride and hydrogen gas are produced.
(b) When iron pieces are added to an aqueous solution of copper sulphate iron being more reactive displaces copper from copper sulphate solution to produce ferrous sulphate.
(c) An aqueous solution of barium chloride, when mixed with dilute sulphuric acid, produces a white insoluble solid barium sulphate and hydrochloric acid.
