The thermal conductivities of acetylene $\left(\mathrm{C}_2 \mathrm{H}_2\right)$ and $\mathrm{N}_2$ at $273 \mathrm{~K}$ and $1 \mathrm{~atm}$ are 0.01866 and $0.0240 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~m}^{-1} \mathrm{~s}^{-1}$, respectively. Based on these data, what is the ratio of the collisional cross section of acetylene relative to $\mathrm{N}_2$ ?
1.33