PLS help me expert

Dear Student

Complete, balanced chemical equation are as follows:
(i) 4NO₂ + O₂ + 2H₂O → 4HNO₃
(ii) 2 HgO → 2 Hg + O₂
(iii) 3 Mg + N₂ → Mg₃N<sub>2

Regards</sub>