What is the total number of neutrons in an atom of o-18?
(1) 18 (3) 10
(2) 16 (4) 8

Iknow #2 is d. i just need to know why

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.

Salt in oceans comes from and of rocks