What information does the following chemical equations convey ?
(a) Zn + H2SO4 → ZnSO4 + H2
(b) Mg + 2HCl → MgCl2 + H2
(a) The first equation conveys that Zinc metal reacts with Sulphuric acid to give rise to Zinc Sulphate and Hydrogen gas. In this reaction, zinc being a more reactive metal displaces Hydrogen from its sulphate solution. So this a displacement reaction.
(b) The second equation conveys that Magnesium reacts with hydrochloric acid to form Magnesium Chloride and Hydrogen gas. Magnesium displaces Hydrogen from its solution, thus it is a displacement reaction.