'A horizontal uniform glass tube of \(100 \mathrm{~cm}\), length sealed at both ends contains \(10 \mathrm{~cm}\) mercury column in the middle. The temperature and pressure of air on either side of mercury column are respectively \(31^{\circ} \mathrm{C}\) and \(76 \mathrm{~cm}\) of mercury. If the air column at one end is kept at \(0^{\circ} \mathrm{C}\) and the other end at \(273^{\circ} \mathrm{C}\), then the pressure of air which is at \(0^{\circ} \mathrm{C}\) is : (in \(\mathrm{cm}\) of \(\mathrm{Hg}\) )

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.