# The melting points of a series of compounds are reported. Which of the options likely represents a molecular species? A. 801 ""^@C; B. 1600 ""^@C; C. 1538 ""^@C; D. 0 ""^@C;

My educated (?) guess would be $D$.
Ionic compounds are non-molecular and tend to possess high melting points, and very high boiling points. Refer to the melting point of say $N a C l$, at $801$ ""^@C.
On the other hand, molecular species are composed of discrete molecules, and the interparticle, i.e intermolecular, interactions tend to be much less in magnitude than those observed for non-molecular species. $A$, $B$, and $C$ are contraindicated.