$\text{Sửa Q thành O ạ}$
$\text{Ta có: 2X; 3S; 12O}$
$\text{Cho công thức có dạng:} X_2S_3O_{12}$
$\text{Mà:} \dfrac{M_{X_2S_3O_{12}}}{M_{H_2}}=171$
$\to X_2S_3O_{12}=342\text{(g/mol)}$
$\to X_2(SO_4)_3=342\text{(g/mol)}$
$\to 2X + 96.3=342\text{(g/mol)}$
$\to 2X= 54\text{(g/mol)}$
$\to X= 27\text{(g/mol)}$
$\text{Vậy X là nhôm (Al)}$