Sulfur dioxide $\left(\mathrm{SO}_{2}\right)$ gas diffuses through a stagnant air-film of thickness $2 \mathrm{~mm}$ at 1 bar and $30^{\circ} \mathrm{C}$. The diffusion coefficient of $\mathrm{SO}_{2}$ in air is $1 \times 10^{-5} \mathrm{~m}^{2} \mathrm{~s}^{-1}$. The $\mathrm{SO}_{2}$ partial pressures at the opposite sides of the film are $0.15 \mathrm{bar}$ and $0.05 \mathrm{bar}$. The universal gas constant is $8.314 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$. Assuming ideal gas behavior, the steady-state flux of $\mathrm{SO}_{2}$ in $\mathrm{mol} \mathrm{m}^{-2} \mathrm{~s}^{-1}$ through the air-film is
- $0.077$
- $0.022$
- $0.085$
- $0.057$