Category --------- General chemistry
Sub-category ------- Acid and Base pH
ANSWER
Solution A ------- 9.35
Solution B ---------- 7.1 x 10^-7 mol/L
solution C ---------- 3.11
EXPLANATION
pH measures the degree of acidity and alkalinity of a substance.
For part A
The hydroxonium ion of the solution is 4.5 x 10^-10 mol/L
Recall,
[tex]pH\text{ = -log }\lbrack\text{ H}_3O^+\rbrack[/tex][tex]\begin{gathered} \text{ pH = -log }\lbrack\text{ 4.5 }\times\text{ 10}^{-10}\rbrack \\ \text{ pH = 9.35} \end{gathered}[/tex]For solution B
The pH of the solution is 6.15
[tex]\begin{gathered} \text{ pH = -log }\lbrack\text{ H}_3O^+\rbrack \\ \text{ 6.15 = -log }\lbrack\text{ H}_3O^+\rbrack \\ \text{ }\lbrack\text{ H}_3O^+\rbrack\text{ = 10}^{-6.15} \\ \lbrack\text{ H}_3O^+\rbrack\text{ = 7.1}\times\text{ 10}\frac{^{-7\text{ }}mol}{L} \end{gathered}[/tex]For solution C
The hydroxonium ion is 7.8 x 10^-4 mol/L
[tex]\begin{gathered} \text{ pH = -log }\lbrack H_3O^+\rbrack \\ \text{ pH = -log }\lbrack\text{ 7.8 }\times\text{ 10}^{-4}\rbrack \\ \text{ pH = 3.11} \end{gathered}[/tex]