Sulphur dioxide and oxygen were allowed to diffuse through a porous partition .$\;20\;dm^{3}\;$ of $\;SO_{2}\;$ diffuses through the porous partition in 60 seconds .The volume of $\;O_{2}\;$ in $\;dm^{3}\;$ which diffuses under the similar condition in 30 seconds will be (atomic mass of sulphur =32 u):

Question

$(a)\;7.09\qquad(b)\;14.1\qquad(c)\;10.0\qquad(d)\;28.2$