In which reaction is there a change in the oxidation state?

In the reaction $X^- + XO_3^- + H^+ \longrightarrow X_2 + H_2O$,the molar ratio in which $X^-$ and $XO_3^-$ react is:

The product of oxidation of $I^{-}$ with $MnO_4^{-}$ in alkaline medium is

The number of electrons involved in the reduction of $Cr_2O_7^{2-}$ in acidic solution to $Cr^{3+}$ is

Which of the following is a redox reaction?
$(i) \, CdCl_2 + 2 KOH \longrightarrow Cd(OH)_2 + 2 KCl$
$(ii) \, BaCl_2 + K_2SO_4 \longrightarrow BaSO_4 + 2 KCl$
$(iii) \, CaCO_3 \longrightarrow CaO + CO_2$
$(iv) \, 2 Ca + O_2 \longrightarrow 2 CaO$

Which product is obtained during the reaction of $MnO_4^-$ with $I^-$ in a faintly alkaline condition?