Question

Are binary molecular compounds generally composed of a metal and a nonmetal?

Answer 1

No - generally nonmetals

Explanation:

The words "molecular compound" implies the compound is held together by covalent bonds (chemical bonds.....sharing of electrons).

Ionic compounds, on the other hand, are composed of ions that interact with each other through +/- interactions (something analogous to the N end of a magnet "sticking" to the S end of a magnet).

Binary Molecular Compounds are covalently bonded compounds that consist of 2 atoms, and these atoms are usually (almost always) nonmetals (think upper right side of periodic table, and H).
Things like Water `H_2O`, `CO_2`, all alkanes `C_NH_"2N+2"` and alkenes, for that matter `C_NH_"2N"`.

Binary Ionic Compounds would be things like NaCl, `MgC_2`, and they are generally made by combinations of Metals + Nonmetals (left and right sides of periodic table).