What is the equivalent weight of $K_2Cr_2O_7$ during the iodometric standardization of $Na_2S_2O_3$?

When $SO_{2}$ is passed through acidified $K_{2}Cr_{2}O_{7}$,the process that takes place is

In the reduction of dichromate by $Fe(II)$,the number of electrons involved per chromium atom is:

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$(NH_4)_2Cr_2O_7 \xrightarrow{\Delta} N_2 \uparrow + Cr_2O_3 \downarrow + 4H_2O \uparrow$

If the molecular weights of $Na_2S_2O_3$ and $I_2$ are $M_1$ and $M_2$ respectively, then what will be the equivalent weights of $Na_2S_2O_3$ and $I_2$ in the following reaction?
$2S_2O_3^{2-} + I_2 \longrightarrow S_4O_6^{2-} + 2I^-$

Assign $A, B, C, D$ from the given type of reaction:
$2KMnO_4 \xrightarrow{\Delta} K_2MnO_4 + MnO_2 + O_2 \uparrow $