Anyone wanna talk im having a really hard time rn and i just cant rn

What element breaks down into yttrium-90?

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.

Which activity is an innate behavior