Write the balanced chemical equation for the following:
(a) Action of heat on manganese dioxide and concentrated hydrochloric acid.
(b) Zinc reacts with dilute hydrochloric acid to form zinc chloride.
(a) MnO2 + 4HCl ⟶ MnCl2 + 2H2O + Cl2↑
(b) Zn + 2HCl ⟶ ZnCl2 + H2↑
