I need help with this question

Which mathematical relationship should you us to convert moles of a substance into grams

12. calculate the hydroxide ion concentration of a solution with ph = 3.25. show all calculations leading to an answer

13. a covalent bond between two atoms is likely to be polar if: a. one of the atoms is much more electronegative than the other. b. the two atoms are equally electronegative. c. the two atoms are of the same element. d. the bond is part of a tetrahedrally shaped molecule. e. one atom is an anion.