Answer:check explanation
Explanation:
No diagram is given above but to determine the value of melting point we need to understand the fact that NaCl has a lower melting point than MgS.
Reasons are; (1) sodium ion (+1) in the first group of the periodic table is characterized by its softness and low melting point and, (2). Is that it has a lower melting point than MgS because the COULUMBIC ATTRACTIONS between its singly charged sodium ions(+1) and the chlorine ions(-1) are weaker than those between the ions in MgS.