Calculate the value of $n$ in the given reaction:
$MnO_4^{-} + 8H^{+} + n e^{-} \to Mn^{+2} + 4H_2O$

Consider the following statements:
In the chemical reaction:
$MnO_2 + 4HCl \to MnCl_2 + 2H_2O + Cl_2$
$(1)$ Manganese ion is oxidised
$(2)$ Manganese ion is reduced
$(3)$ Chloride ion is oxidised
$(4)$ Chloride ion is reduced.
Which of these statements are correct?

For the redox reaction $Zn + NO_3^{-} \rightarrow Zn^{+2} + NH_4^{+}$,the coefficients of $NO_3^{-}$,$Zn$,and $H^{+}$ in the balanced equation are respectively:

The equivalent weight of $MnSO_4$ is half of its molecular weight when it is converted to

The number of moles of electrons required to reduce $0.2 \ mol$ of $Cr_2O_7^{2-}$ to $Cr^{3+}$ is:

Assign $A, B, C, D$ from given type of reaction.
$CuSO_4(aq.) + Zn(s) \longrightarrow ZnSO_4(aq.) + Cu(s)$