\(a,Na+H_2O\rightarrow NaOH+\dfrac{1}{2}H_2\\ b,Zn+2HCl\rightarrow ZnCl_2+H_2\\ c,P_2O_5+3H_2O\rightarrow2H_3PO_4\\ d,3Fe+2O_2\xrightarrow[]{t^o}Fe_3O_4\)
\(Na+H_2O\rightarrow NaOH+\dfrac{1}{2}H_2\\ Zn+2HCl\rightarrow ZnCl_2+H_2\\ P_2O_5+3H_2O\rightarrow2H_3PO_{\text{ 4}}\\ 3Fe+2O_2\underrightarrow{t^o}Fe_3O_4\)
a,Na+H2O→NaOH+12H2b,Zn+2HCl→ZnCl2+H2c,P2O5+3H2O→2H3PO4d,3Fe+2O2to→Fe3O4