Final answer:
Element X, which lies between elements Q and Z in the same group on the periodic table, is expected to have a melting point closer to -7°C than to -219°C due to the trend of increasing melting points within a group.
Step-by-step explanation:
The question involves the concept of trends in the melting points of elements within the same group on the periodic table. Considering that element Q has a melting point of -219°C and element Z has a melting point of -7°C, it is reasonable to infer that element X, being in the same group and having an atomic number between that of Q and Z, would have a melting point that falls between the two values. Given that the melting point generally increases with atomic number within a group, the melting point of element X is likely to be closer to the melting point of element Z rather than Q.