d
The left side of the container has a gas, let having molecular wt. \(M_{1}\) Right part has Mol. wt \(=M_{2}\)

Temperature of both left and right chambers are equal as the separating wall is diathermic

\(\sqrt{\frac{3 R T}{M_{1}}}=\sqrt{\frac{8 R T}{\pi M_{2}}} \Rightarrow \frac{3 R T}{M_{1}}=\frac{8 R T}{\pi M_{2}} \Rightarrow \frac{M_{1}}{\pi M_{2}}\)

\(= \frac{3}{8} \Rightarrow \frac{M_{1}}{ M _{2}}=\frac{3 \pi}{8}=1.1775 \approx 1.18\)