a) Xét trong 1 (mol) hỗn hợp X.
\(\Rightarrow\left\{{}\begin{matrix}n_{H2}=0,5\left(mol\right)\\n_{O2}=0,25\left(mol\right)\\n_{SO_x}=0,25\left(mol\right)\end{matrix}\right.\)
=> mhỗn hợp X = mH2 + mO2 + mSOx = 0,5 x 2 + 0,25 x 32 + 0,25(32+ 16x) = 17 + 4x (gam)
Mặt khác: %mSOx =\(\dfrac{0,25\left(32+16x\right)}{17+4x}=68,956\%\)
=> x = 3
=> CTHH: SO3
b)dSO3/O2 = \(\dfrac{80}{32}=25\)