Explain how the formulas for H2O and NaCl provide different information about the composition of these two compounds.

Question

What I think:
For every 1 atom of oxygen, there are 2 atoms of hydrogen. For every one atom of sodium there is one atom of chlorine.

Answer 1

If the problem means by "information" composition then what you have written is ok. I might make it clear that this is for the empirical formula shown; i.e., one molecule.