\(n_{NaOH}=\dfrac{12}{40}=0.3\left(mol\right)\)
\(a.\)
\(2NaOH+SO_2\rightarrow Na_2SO_3+H_2O\)
\(0.3.............0.15\)
\(n_{SO_2}\le0.15\)
\(\Rightarrow V\le3.36\left(l\right)\)
\(b.\)
\(NaOH+SO_2\rightarrow NaHSO_3\)
\(0.3...........0.3\)
\(n_{SO_2}\ge0.3\)
\(\Rightarrow V\ge6.72\left(l\right)\)
\(c.\)
Cả 2 muối
\(\Rightarrow3.36< V< 6.72\)