Question

Boiling and melting point of Zn, Hg and Cd are low due to

• A. partially filled d-orbital
• B. absence of unpaired electrons
• C. poor shielding of d-orbital
• D. higher nuclear charge

Answer 1

The correct option is B absence of unpaired electrons

Generally, greater the number of unpaired electrons, higher is the melting point.
Similary, greater the number of unpaired electron, stronger will be the bonding and higher will be the boiling point.
Thus, for a transition metal to have high boiling and melting point it should possess more number of unpaired electrons.

In Zn, Cd and Hg the d-orbital and valence s orbital are fully filled. They dont have any unpaired electrons, so their melting and boiling points are very low.
Hence, option (b) is correct.