a.
\(\left(1\right)Fe+2HCl--->FeCl_2+H_2\)
\(\left(2\right)FeCl_2+2NaOH--->2NaCl+Fe\left(OH\right)_2\)
\(\left(3\right)4Fe\left(OH\right)_2+O_2+2H_2O\overset{t^o}{--->}4Fe\left(OH\right)_3\)
\(\left(4\right)2Fe\left(OH\right)_3\overset{t^o}{--->}Fe_2O_3+3H_2O\)
\(\left(5\right)Fe_2O_3+6HCl--->2FeCl_3+3H_2O\)
b.
\(\left(1\right)4Al+3O_2\overset{t^o}{--->}2Al_2O_3\)
\(\left(2\right)Al_2O_3+6HCl--->2AlCl_3+3H_2O\)
\(\left(3\right)AlCl_3+3NaOH--->Al\left(OH\right)_3+3NaCl\)
\(\left(4\right)2Al\left(OH\right)_3\overset{t^o}{--->}Al_2O_3+3H_2O\)
\(\left(5\right)Al_2O_3+3H_2SO_4--->Al_2\left(SO_4\right)_3+3H_2O\)