Respuesta :
What you need to do is find the Molar mass of sodium and then divide your mass (0.25g) by the molar mass of Na.
Therefore 0.25g/22.9898g/mol (do you see how the "grams" unit will cancel out? That will leave you with the number of moles you have.
Therefore 0.25g/22.9898g/mol (do you see how the "grams" unit will cancel out? That will leave you with the number of moles you have.