99.9885 % 1H with a mass of 1.007825 amu and 0.0115 % 2H with a mass of 2.014102 amu.

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

if you need further assistance, let me know: )

~ trueboss72

it’s previous models   because when i picked that son of a gun’s answer it was wrong look for previous models because they might make it a different letter  

the answer is a! (2.9 x 10^-18 j) hope i could someone. : )