a glass rod obtains a positive chartge from being rubbed by silk. Is this due to the glass gaining protons, or losing electrons?

Answer: The positive charge is due to loss of electrons by the glass rod.

Explanation:

According to the atomic theory, the protons of an atom are much closer to the nucleus than the electrons.

The nucleus itself exerts force on the protons to keep it from being lost.

On the other hand, electrons orbit on the outer part of the atom - much farther from the nucleus (electrons in the outermost shell being more so)

Hence, it is much easier for the glass rod to lose its outermost electrons due to less impact of the nuclear forces on those electrons