When silver nitrate is heated to red hot,what is formed?

Assign $A, B, C, D$ from the given type of reaction.
$Ba(OH)_2 + CO_2 \longrightarrow BaCO_3 \downarrow + H_2O$

$KMnO_4$ (acidified) $+ HCl \rightarrow H_2O + X_{(g)},$ $X$ is a

$X(aq.) + Na_2O_2 \to Y(aq.) \xrightarrow{BaCl_2} Z \downarrow_{\text{Insoluble in dil. } HCl}$
$X$ and $Y$ are different sodium salts. Then the anion present in the salt $(X)$ is:

Identify the substance oxidised,reduced,oxidising agent,and reducing agent for each of the following reactions:
$(a)$ $2AgBr_{(s)} + C_6H_6O_{2(aq)} \to 2Ag_{(s)} + 2HBr_{(aq)} + C_6H_4O_{2(aq)}$
$(b)$ $HCHO_{(l)} + 2[Ag(NH_3)_2]^+_{(aq)} + 3OH^-_{(aq)} \to 2Ag_{(s)} + HCOO^-_{(aq)} + 2NH_{3(aq)} + 2H_2O_{(l)}$
$(c)$ $HCHO_{(l)} + 2Cu^{2+}_{(aq)} + 5OH^-_{(aq)} \to Cu_2O_{(s)} + HCOO^-_{(aq)} + 3H_2O_{(l)}$
$(d)$ $N_2H_{4(l)} + 2H_2O_{2(l)} \to N_{2(g)} + 4H_2O_{(l)}$
$(e)$ $Pb_{(s)} + PbO_{2(s)} + 2H_2SO_{4(aq)} \to 2PbSO_{4(s)} + 2H_2O_{(l)}$

Assign $A, B, C, D$ from the given type of reaction.
$K_2Cr_2O_7 + 2NaOH \longrightarrow 2K_2CrO_4 + H_2O$
Identify the nature of the product $CrO_4^{2-}$ formed in the reaction.