Comment on the reactions of dihydrogen with: (i) chlorine (ii) sodium and (iii) copper (II) oxide. 

(i) With chlorine. H₂ reduces chlorine into chloride (Cl^-) ion and itself get oxidised to H⁺ ion by chlorine to form HCl. An electron pair is shared between H and Cl leading to the formation of a covalent molecule.
H₂ +Cl₂ --> 2HCl
(ii) With sodium. H₂ is reduced by sodium to form NaH. An electron is transferred from Na to H leading to the formation of Na⁺H^- (ionic compound).
(iii) With copper (II) oxide. H₂ reduces copper (II) oxide to copper and itself gets oxidised to H₂O, which is a covalent molecule.
CuO +H₂ ---> Cu +H₂O