$AgCl$ on fusion with $Na_2CO_3$ forms

In the redox reaction $2MnO_4^- + 5C_2O_4^{2-} + 16H^{+} \rightleftharpoons 2Mn^{2+} + 10CO_2 + 8H_2O$,the ion acting as autocatalyst is

Which of the following will not change the orange colour of $K_2Cr_2O_7$ into green colour in an acidic medium?

Which of the following oxidation reactions are carried out by both $K_2Cr_2O_7$ and $KMnO_4$ in acidic medium?
$A. I^{-} \rightarrow I_2$
$B. S^{2-} \rightarrow S$
$C. Fe^{2+} \rightarrow Fe^{3+}$
$D. I^{-} \rightarrow IO_3^-$
$E. S_2O_3^{2-} \rightarrow SO_4^{2-}$
Choose the correct answer from the options given below:

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$Cu^{2+} (aq.) + 2I^{-} \longrightarrow CuI \downarrow + \frac{1}{2}I_2$

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$CaSO_3(s) + H_2SO_4(aq) \longrightarrow CaSO_4(s) + SO_2(g) + H_2O(l)$