When an excess of $KI$ is added to a $CuSO_4$ solution and then $Na_2S_2O_3$ is added to the mixture,which of the following statements is incorrect?

How would you account for the increasing oxidising power in the series $VO_2^+ < Cr_2O_7^{2-} < MnO_4^-$?

How would you account for the following:
$(i)$ Of the $d^{4}$ species,$Cr^{2+}$ is strongly reducing while $Mn^{3+}$ is strongly oxidising.
$(ii)$ $Co^{2+}$ is stable in aqueous solution but in the presence of complexing reagents it is easily oxidised.
$(iii)$ The $d^{1}$ configuration is very unstable in ions.

The highest oxidation state of $Mn$ is shown by

How are transition metals and their oxides used in industrial processes?

Consider the following transformation $2 \ CuX_2 \xrightarrow[\text{Room}]{\text{temp.}} Cu_2X_2 + X_2 \uparrow$. Then $X^{-}$ can be: