H2(SO)4+MgCl2->H2O4Cl
HCOH + 2Cu(OH)2 (t)= HCOOH + Cu2O + 2H2O
75/30 = x/46
x = 115 г
4AL + 3O2 =2 Al2O3
Ca + 2H2O = Ca(OH)2 + H2
2Na + 2H2O = 2NaOH + H2
Zn + H2O = ZnO + H2
SO2 + H2O = H2SO3
MgO + H2O = Mg(OH)2