Balancing Redox Reactions — Prelims Questions

Which of the following balanced equations correctly represents the reaction of dichromate ion with iodide ion in acidic medium? $Cr_2O_7^{2-} + I^- \rightarrow Cr^{3+} + I_2$

Balance the following reaction in basic medium: $MnO_4^- + C_2O_4^{2-} \rightarrow MnO_2 + CO_3^{2-}$

In the reaction $P_4 + OH^- + H_2O \rightarrow PH_3 + H_2PO_2^-$, what is the change in oxidation number of phosphorus during its oxidation?

How many electrons are transferred in the balanced reaction: $MnO_4^- + 5Fe^{2+} + 8H^+ \rightarrow Mn^{2+} + 5Fe^{3+} + 4H_2O$?

In the reaction $Zn + HNO_3 \rightarrow Zn(NO_3)_2 + N_2O + H_2O$, what is the stoichiometric coefficient for $HNO_3$ when the equation is balanced?

Which of the following statements is INCORRECT regarding balancing redox reactions?

When $KMnO_4$ reacts with $H_2S$ in an acidic medium, the products are $Mn^{2+}$, $S$, and $H_2O$. What is the coefficient of $H_2S$ in the balanced equation?