[venom1221]

How many mols of O are in HSO4??
Is it 1 because it is 1 mol of HSO4 or 4?

[mike]

Do you mean H2SO4?
Either way, if you have one mole of HSO4 then the molecule contains one mole of H, one mole of S and 4 moles of O.

Remember the mole is similar to the "dozen" so one dozen (12) HSO4 molecules contains 4 dozen (48) O atoms.

other examples:

1 mole H2O = 2 moles of H and 1 mole of O.
1 mole of HCl = 1 mole of H and 1 mole of Cl etc etc

[Borek]

That's a little bit tricky question. Are you asked about moles of O or moles of O₂ - remember that oxygen is diatomic. While it is perfectly OK to ask about O, check precise wording of the question.