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Explanation:

1. 4×10^5

2. 6×10^-4

3. 2.1995×10^7

4. 5.050×10^-2

5. 7280

6. 0.00003608

7. 940.9

8. 0.0015

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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.

the answer to this question is 3.