Question 10
Taking the chapter as a whole, what single fact about a compound accounts for its melting point, its conductivity and its state at room temperature?
The right answer is the one marked above.
Whether its electrons were transferred or shared. Transfer gives ions and an ionic lattice, and with it a high melting point and conduction when molten or dissolved. Sharing gives molecules, weak forces between them, and low melting points.
The number of atoms in a molecule and the mass of those atoms are real facts but do not decide these properties — sodium chloride and water are both small, and behave completely differently. Where a compound came from makes no difference at all.