Here we assume that disintegration has occur so the normal t½ formular will not be used
mathematically we..⅛×5600 =700
therefore it is about 700years option A
C. Move one electron from sodium to fluorine, because the element with the smallest amount of valence electrons is the one that give away the electrons, it is easier to add one to seven than it is to add 7 to one. I just learned this in physics, hope it helps! If you need more explaining I can do that.
