1) Mg+O₂₋>MgO 2) P+Cl₂₋>PCl₃ 3) HgO₋>O₂+Hg 4) AgBr₋>
Mg+O2=>2MgO 2P+3Cl2=>2PCl3 2HgO=>O2+2Hg AgBr=>Ag+Br