If the hydrogen ion concentration, [H+], in a solution is 5.39 x 10-8 M,
what is [OH-]?
1.86 x 1021 M
1.86 x 10-7 M

well in order to answer this question you have to provide more information < 3

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8