At \(700 \mathrm{~K}\), the Equilibrium constant value for the formation of \(\mathrm{HI}\) from \(\mathrm{H}_2\) and \(\mathrm{I}_2\) is 49.0 .
0.7 mole of \(\mathrm{HI}(\mathrm{g})\) is present at equilibrium. What will be the concentrations of \(\mathrm{H}_2\) and \(\mathrm{I}_2\) gases if we initially started with \(\mathrm{HI}(\mathrm{g})\) and allowed the reaction to reach equilibrium at the same temperature?

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.