Here it is written that order decreases from top to bottom in a group but order is given opposite to what written
Melting or boiling points depends on effectiveness of metallic bonding in atoms.
Smaller the size of atoms more strong the metallic bond is .
So down the group as size increases bond strength decreases.As a result mp/bp decreases down the grp.(down elements can easily melt /boil as their bond is weaker)