Question

The highest melting point among alkali metal is:

• A. $Li$
• B. $Na$
• C. $K$
• D. $Rb$

Answer 1

The correct option is A $Li$

$Li$ has highest melting point among alkali metals. All metals have low melting point than $Li$. The melting point decreases down the group. The low melting point are attributed to their larger atomic size due to which the binding energies of their atoms in the crystal lattice are low. So the melting point decreases from $Li$ to $Rb$.
Hence option (a) is correct.