If you compare the mass of a substance before and after a
change, what will you find?
A. The mass before is greater than after.
B. The mass before equals the mass after.
C. The mass after is greater than before.

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

i belive it is water

the objects have the same charge.