In the human body,if necessary,the plates,screws,or wires used for surgery are made up of:

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.

$Cu^{2+}$ ions will be reduced to $Cu^{+}$ ions by the addition of an aqueous solution of

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

Vanadium $(III)$ oxide $(V_2O_3)$ is a strong:

The nature of oxides $V_{2}O_{3}$ and $CrO$ is indexed as '$X$' and '$Y$' type respectively. The correct set of $X$ and $Y$ is: