Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$SrCrO_4 \downarrow + 2AcOH \text{ (Excess)} \longrightarrow Sr(AcO)_2 + H_2Cr_2O_7$

Upon the addition of a solution $A$ to a strongly acidified solution of barium nitrate,a white precipitate was obtained which did not dissolve even after large addition of water. Solution $A$ contained

$Cu^{2+}(aq.)$ does not undergo a redox reaction with a solution of:

Assign $A, B, C, D$ from the given type of reaction.
$2KI + HgI_2 \downarrow \longrightarrow K_2[HgI_4]$

Identify the substance oxidised,reduced,oxidising agent,and reducing agent for each of the following reactions:
$(a)$ $2 AgBr_{(s)} + C_6 H_6 O_{2(aq)} \rightarrow 2 Ag_{(s)} + 2 HBr_{(aq)} + C_6 H_4 O_{2(aq)}$
$(b)$ $HCHO_{(l)} + 2 [Ag(NH_3)_2]^+_{(aq)} + 3 OH^-_{(aq)}$ $\rightarrow 2 Ag_{(s)} + HCOO^-_{(aq)} + 4 NH_{3(aq)} + 2 H_2 O_{(l)}$
$(c)$ $HCHO_{(l)} + 2 Cu^{2+}_{(aq)} + 5 OH^-_{(aq)} \rightarrow Cu_2 O_{(s)} + HCOO^-_{(aq)} + 3 H_2 O_{(l)}$
$(d)$ $N_2 H_{4(l)} + 2 H_2 O_{2(l)} \rightarrow N_{2(g)} + 4 H_2 O_{(l)}$
$(e)$ $Pb_{(s)} + PbO_{2(s)} + 2 H_2 SO_{4(aq)} \rightarrow 2 PbSO_{4(s)} + 2 H_2 O_{(l)}$

In which of the following reactions does $HNO_3$ $NOT$ act as an oxidizing agent?