Question
Name the indicator used in redox titration involving $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ as an oxidising agent.
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| Elements | $\Delta\text{H}_{1}$ | $\Delta{\text{H}}_{2}$ | $\Delta_{\text{eg}}\text{H}$ |
| I | 520 | 7300 | -60 |
| II | 419 | 3051 | -48 |
| III | 1681 | 3374 | -328 |
| IV | 1008 | 1846 | -295 |
| V | 2372 | 5251 | +48 |
| VI | 738 | 1451 | -40 |