STEP-BY-STEP EXPLANATION:
Firstly, we need to write out the electronic configuration of potassium and calcium atom
[tex]\begin{gathered} _{19}K=1s^22s^22p^63s^23p^64s^1 \\ _{20}Ca=1s^22s^22p^63s^23p^64s^2 \end{gathered}[/tex]According to the above configuration, we observe that potassium has one valence electron and calcium has two valence electrons. This implies that potassium belongs to group 1 and calcium belongs to group 2.
In addition, each atom in calcium has a stronger attraction to the delocalized electrons than potassium. Also, more energy is required to break the bond in calcium. Hence, calcium will have high melting point than potassium.
