Final answer:
The melting point of a pure compound should be within a narrow range, usually within 1-2 degrees Celsius. Melting points depend on the strength of the forces within the solid and vary significantly among different materials, such as ionic and molecular compounds.
Step-by-step explanation:
The melting point of a pure compound is a specific temperature at which the compound transitions from a solid to a liquid. This physical property is an indication of the purity of the substance. For a pure compound, the melting point range should be relatively narrow, typically within 1-2 degrees Celsius. A broad or wide melting point range can indicate impurities within the compound. It is not exactly specified in the question what the expected melting point range of the hypothetical compound is, so direct reference to options like 'between 200 and 250 K' seems out of context. However, some typical examples mentioned indicate that Sodium chloride (NaCl) has a melting point of 801°C, and Ice (solid H₂O) melts at 0°C, highlighting that the melting point is highly dependent on the strength of forces within the solid.
Melting points of molecular compounds are generally lower than those of ionic compounds due to the differing strengths of their intermolecular forces. As a rule, ionic compounds do not conduct electricity in the solid state but can conduct when melted or dissolved in water. Substances that are generally water-soluble include ionic compounds and polar molecular compounds.