(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