Phenolphthalein does not act as an indicator for the titration between

For the redox reaction $MnO_4^- + C_2O_4^{2-} + H^{+} \to Mn^{2+} + CO_2 + H_2O$,the correct coefficients of the reactants for the balanced reaction are:
$MnO_4^-$ : $C_2O_4^{2-}$ : $H^{+}$

Balance the following redox reactions using the oxidation number and ion-electron method:
$(1) H_2S + Fe^{3+} \to Fe^{2+} + S + H^{+}$
$(2) Cu + NO_3^{-} \to Cu^{2+} + NO_2$
$(3) Sn + NO_3^{-} + H^{+} \to Sn^{2+} + NH_4^{+} + H_2O$
$(4) As + NO_3^{-} + H^{+} \to AsO_4^{3-} + NO_2 + H_2O$

Explain the balancing of a redox reaction by the half-reaction method with a suitable example.

Consider the reaction of water with $F_{2}$ and suggest,in terms of oxidation and reduction,which species are oxidized and which are reduced.

The product of $I^-$ with $MnO_4^-$ in acidic medium is