$3d^{10}4s^0$ electronic configuration is exhibited by

Statement-$I$: Mercury is liquid at room temperature.
Statement-$II$: In mercury,there is no unpaired $d$-electron and thus,metallic bonding is weakest.

An element of the $3d-$ transition series shows two oxidation states $x$ and $y$,which differ by two units. Then:

In which of the following transition metal ions is $d-d$ transition possible?

$A$ chloro compound of vanadium has a spin-only magnetic moment of $1.73 \ BM$. This vanadium chloride has the formula:

For the four consecutive transition elements $Cr, Mn, Fe,$ and $Co$,the correct order of stability of their $+2$ oxidation state is: