$20 \, mL$ of $0.02 \, M \, K_2Cr_2O_7$ solution is used for the titration of $10 \, mL$ of $Fe^{2+}$ solution in the acidic medium. The molarity of $Fe^{2+}$ solution is ........... $\times 10^{-2} \, M$ (Nearest Integer).

Consider the following list of reagents:
Acidified $K_2Cr_2O_7$,alkaline $KMnO_4$,$CuSO_4$,$H_2O_2$,$Cl_2$,$O_3$,$FeCl_3$,$HNO_3$ and $Na_2S_2O_3$. The total number of reagents that can oxidise aqueous iodide to iodine is

Justify that the following reactions are redox reactions:
$(a) \ CuO_{(s)} + H_{2(g)} \to Cu_{(s)} + H_2O_{(g)}$
$(b) \ Fe_2O_{3(s)} + 3CO_{(g)} \to 2Fe_{(s)} + 3CO_{2(g)}$
$(c) \ 4BCl_{3(g)} + 3LiAlH_{4(s)} \to 2B_2H_{6(g)} + 3LiCl_{(s)} + 3AlCl_{3(s)}$
$(d) \ 2K_{(s)} + F_{2(g)} \to 2K^+F^-_{(s)}$
$(e) \ 4NH_{3(g)} + 5O_{2(g)} \to 4NO_{(g)} + 6H_2O_{(g)}$

Acidified $KMnO_4$ can be decolourised by

Assign $A, B, C, D$ from the given type of reaction.
$Sr(AcO)_2 + Ag_2SO_4 \longrightarrow 2AcOAg \downarrow + SrSO_4 \downarrow$

Identify the redox reactions among the following and determine the oxidizing and reducing agents in them:
$(a) 3HCl_{(aq)} + HNO_{3_{(aq)}} \to Cl_{2_{(g)}} + NOCl_{(g)} + 2H_2O_{(l)}$
$(b) HgCl_{2_{(aq)}} + 2KI_{(aq)} \to HgI_{2_{(s)}} + 2KCl_{(aq)}$
$(c) Fe_2O_{3_{(s)}} + 3CO_{(g)} \xrightarrow{\Delta} 2Fe_{(s)} + 3CO_{2_{(g)}}$