$K_2Cr_2O_7$ paper acidified with dilute $H_2SO_4$ turns green when exposed to

What is the oxidation state of chromium in the final product when $KI$ reacts with acidified potassium dichromate solution?

Assign $A, B, C, D$ from the given type of reaction.
$KMnO_4 + NaNO_3 \longrightarrow$ No reaction

What is the equivalent weight of the reductant in the reaction $2[Fe(CN)_6]^{3-} + H_2O_2 + 2OH^{-} \rightarrow 2[Fe(CN)_6]^{4-} + 2H_2O + O_2$? (Given: $Fe = 56, C = 12, N = 14, O = 16, H = 1$)

Assign $A, B, C, D$ from the given type of reaction.
$NO + NO_2 \xrightarrow{-11 \ ^{\circ}C} N_2O_3$

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$FeSO_4 + Na_2S \longrightarrow FeS \downarrow$