Which of the following cannot pass across the placenta?
(a) oxygen
(b) waste materials
(c) blood
(d) nutrients

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.

1.43 x 10^-11 j the guy commented the awnser just making sure u see it .