The correct option is C 14.1
Let r1, M1 be the rate of diffusion and Molecular weight of SO2 and r2,M2 be the rate of diffusion and Molecular weight of O2.
Let V dm3 of O2 diffusion in 30 sec.
∴r1=2060,r2=V30,M1=64,M2=32
r1r2=√M2M1⇒13V30=√3264
⇒10V=√12 ⇒10×10V2=12
⇒V2=200 or, V=√200=14.1 dm3