Addition of iron filings to $CuSO_4$ solution causes the precipitation of $Cu$ due to the:

In acid solution,the reaction $MnO_4^- \to Mn^{2+}$ involves

Observe the following reactions:
$I$. $2H_2O_{(l)} + 2Na_{(s)} \rightarrow 2NaOH_{(aq)} + H_{2(g)}$
$II$. $2H_2O_{(l)} + 2F_{2(g)} \rightarrow 4H^{+}_{(aq)} + 4F^{-}_{(aq)} + O_{2(g)}$
Identify the correct statement from the following:

Identify the element reduced in the following reaction: $Cr_2O_7^{2-} + 14H^{+} + 6I^{-} \longrightarrow 2Cr^{3+} + 7H_2O + 3I_2$

Reduction involves

In an acidic medium,when $KMnO_4$ is reduced by oxalic acid,what is the change in the oxidation state of $Mn$?