a)

`2 xx |`$\mathop{M}\limits^{0}$ `->` $\mathop{M}\limits^{+n}$ $\rm + ne$

`n xx |` $\mathop{S}\limits^{+6}$ $\rm + 2e$ `->` $\mathop{S}\limits^{+4}$

`=> 2M + 2nH_2SO_4 -> M_2(SO_4)_n + nSO_2 + 2nH_2O`

b)

`n_{SO_2} = (3,2227)/(24,79) = 0,13` mol

BTe

`=> n xx n_M = 2n_{SO_2}`

`=> n_M = 2/n xx n_{SO_2} = (0,26)/(n)` mol

`=> M_M = (2,34)/((0,26)/(n)) = 9n(g//mol)`

Cho `n = 3 => M = 27(Al)`

Vậy kl M là `Al`