Question

On moving across a transition series, the melting points first ______, attain a ______ value and then ______.

Answer 1

On moving across a transition series, the melting points first increase, attain a maximum value and then decrease.

Explanation:

This trend is due to the increase in metallic bonding strength caused by unpaired d-electrons. As more d-electrons pair up towards the middle of the series, bonding becomes strongest, giving high melting points, which later decrease as pairing reduces bonding strength.