What happens when Barium (Ba), in group 2, reacts with oxygen (O) which is in group 6?

barium oxide

Explanation: The barium will give some of it's electrons up to the oxygen, and then they will both reach the stability of a noble gas. Then, they will both combinate to barium oxide, so the answer is barium oxide.

the answer is definitely c.

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.