$c.$

$\text{ x 2 | }$$\mathop{Fe}\limits^{+2} + \mathop{2S}\limits^{-1}\to\mathop{Fe}\limits^{+3}+\mathop{2S}\limits^{+4}+11e$

$\text{ x 11 | }$$\mathop{S}\limits^{+6}+2e \to \mathop{S}\limits^{+4}$

`->`$2FeS_2+14H_2SO_4(đ)  \to Fe_2(SO_4)_3+15SO_2+14H_2O$

$d.$

Dùng sơ đồ đường chéo hoặc biến đổi như sau:

$M=16.75 \times 2=33.5$

`->`$\dfrac{30n_{NO}+44n_{N_2O}}{n_{NO}+n_{N_2O}}=33.5$

`<=>`$30n_{NO}+44n_{N_2O}=33.5n_{NO}+33.5n_{N_2O}$

`=>`$\dfrac{n_{NO}}{n_{N_2O}}=\dfrac{33.5-44}{30-33.5}=3$

$\text{ x 17 | }$$\mathop{Al}\limits^{0} \to Al^{3+}+3e$

$\text{ x 3 | }$$\mathop{5N}\limits^{+5}+17e \to \mathop{3N}\limits^{+2}O+\mathop{N_2}\limits^{+1}O$

`->`$17Al+66HNO_3 \to 17Al(NO_3)_3+9NO+3N_2O+33H_2O$

`M_{khí}=16,75.2=33,5(g//mol)`

`->{n_{NO}}/{n_{N_2O}}={44-33,5}/{33,5-30}=3`

`Al->Al^{+3}+3e|xx17`

`5N^{+5}+17e->3N^{+2}+N_2^{+1}|xx3`

`17Al+66HNO_3->17Al(NO_3)_3+9NO+3N_2O+33H_2O`