Question

The number of molecules in 1.0 mole of H2O is _____ as in one mole of O2.

Answer 1

"the same";
One mole of any given thing is 6 * 10²³ of it;
One mole of H₂O is 6 * 10²³ molecules;
One mole of O₂ is also 6 * 10²³ molecules;
Therefore for both substances, there are the same number of molecules.