If an iron rod is dipped in $CuSO_4$ solution,what happens?

$A$ solution of $Na_2S_2O_3$ is standardized iodometrically against $0.167 \ g$ of $KBrO_3$ where $BrO_3^-$ changes to $Br^-$. This process requires $45 \ mL$ of the $Na_2S_2O_3$ solution. What is the strength of the $Na_2S_2O_3$ in $N$?
$[Mw \text{ of } KBrO_3 = 167]$

The number of moles of $KMnO_4$ reduced by one mole of $KI$ in alkaline medium is:

Balance the following redox reactions by the ion-electron method:
$(a)$ $MnO_{4(aq)}^- + I_{(aq)}^- \to MnO_{2(s)} + I_{2(s)}$ (in basic solution)
$(b)$ $MnO_{4(aq)}^- + SO_{2(g)} \to Mn_{(aq)}^{2+} + HSO_{4(aq)}^-$ (in acidic solution)
$(c)$ $H_2O_{2(aq)} + Fe_{(aq)}^{2+} \to Fe_{(aq)}^{3+} + H_2O_{(l)}$ (in acidic solution)
$(d)$ $Cr_2O_7^{2-} + SO_{2(g)} \to Cr_{(aq)}^{3+} + SO_{4(aq)}^{2-}$ (in acidic solution)

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$H_3PO_2 + CuSO_4 + H_2O \longrightarrow Cu + H_3PO_4 + H_2SO_4$

Assign $A, B, C, D$ from the given type of reaction: $C_{(s)} + O_{2(g)} \xrightarrow{\Delta} CO_2 \uparrow$