(3) $2Al + 6HCl \longrightarrow 2AlCl_3 + 3H_2\uparrow$
(4) $Zn + 2HCl \longrightarrow ZnCl_2+H_2\uparrow$
(5) $Cu(OH)_2\xrightarrow{\quad t^\circ\quad} CuO + H_2O$
(6) $Fe + 6HNO3\longrightarrow Fe(NO_3)_3 + 3NO_2\uparrow + 3H_2O$
(7) $Fe + 2HCl\longrightarrow FeCl_2 + H_2\uparrow$
(8) $2C_2H_2 + 5O_2\xrightarrow{\quad t^\circ\quad} 4CO_2\uparrow + 2H_2O$
(9) $3Fe + 2O_2 \xrightarrow{\quad t^\circ\quad} Fe_3O_4$
(10) $2Al(OH)_3 + 3H_2SO_4\longrightarrow Al_2(SO_4)_3 + 3H_2O$
