1. $4K+O_2\to 2K_2O$
2. $2Al+3CuCl_2\to 2AlCl_3+3Cu$
3. $Fe+2AgNO_3\to Fe(NO_3)_2+2Ag$
4. $2Fe+3Cl_2\to 2FeCl_3$
5. $Al+3AgNO_3\to Al(NO_3)_3+3Ag$
6. $2Al+3CuO\to Al_2O_3+3Cu$
7. $6NaOH+Fe_2(SO_4)_3\to 2Fe(OH)_3+3Na_2SO_4$
8. $BaCl_2+2AgNO_3\to 2AgCl+Ba(NO_3)_2$