Loretta and her friends want to find out which of their pets can run the fastest. Which kind of scientific investigation should they use? A. a field study
B. a controlled experiment
C. development of a model
D. a review of existing work

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.

it's all four options.