1.
For the redox reaction,
Cr2O72−+C2O42−+H+→Cr3++CO2+H2O\text{Cr}_2\text{O}_7^{2-} + \text{C}_2\text{O}_4^{2-} + \text{H}^+ \rightarrow \text{Cr}^{3+} + \text{CO}_2 + \text{H}_2\text{O}

the correct whole number stoichiometric coefficients of Cr2O72−\text{Cr}_2\text{O}_7^{2-}, C2O42−\text{C}_2\text{O}_4^{2-} and H+\text{H}^+ are respectively: