Question

Which among d block elements have lowest boiling point and highest boiling point?

Answer 1

d-block elements with more number of unpaired $e^{-}$ have high boiling points as more is the number of unpaired $e^{-}$, stronger is the metallic bonding which results in high enthalpy of atomization. Thus more amount of heat is required to weaken these metallic bonds. Hence having a high boiling point.

So, Chromium with electronic configuration $4s^{1}3d^5$ having $5$ unpaired $e^{-}s$ will have the highest boiling point due to the formation of stronger metallic bonds.

On the other hand, $Zn$ and $Hg$ have lowest boiling point due to the absence of unpaired d-$e^{-}s$.