Question

The melting points and boiling points up to the middle of 3d- series

• A. Increases
• B. Decreases
• C. Remain same
• D. No regular trend

Answer 1

The correct option is A Increases

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, melting and boiling point of 3d metals rise to a maximum at $d^5$ (except for anomalous values of Mn) and then, fall regularly as the atomic number increases.
Hence, option (a) is correct.