(i) Magnesium with dilute hydrochloric acid
(ii) Aluminium with dilute hydrochloric acid
(iii) Zinc with dilute hydrochloric acid
(iv) Iron with dilute hydrochloric acid
Solution:
(i) Mg + 2HCl → 2MgCl2 + H2
(ii) 2Al + 6HCl → 2AlCl3 + 3H2
(iii) Zn + 2HCl → ZnCl2 + H2
(iv) Fe + 2HCl → FeCl2 + H2