Which of the following are simple molecular ions? NH4+ NaCl NO3- CO3 2-

Explanation:

A molecule is a chemical species containing at least two chemically-bonded atoms while an ion is a charged chemical species.

Hence, a molecular ion must be a molecule and must carry a charge (positive or negative).

Given the two criteria above, then are all molecular ions. , although a molecule, is not a molecular ion because it is not charged.