Topic : redox reactions in terms of electron transfer reactions

The number of moles of K₂Cr₂O₇ that will be needed to react with one mole of nitrite ion in acidic solution is

Select the incorrect statement among the following

Ratio of $\text{Cr}_2\text{O}_7^{2-}$ and $\text{SO}_3^{2-}$ in balanced redox reaction for acidic medium is

Which of the following on heating give(s) brown colour gas?