13. At 25 ℃, a solution is formed by mixing 50.0 mL of 0.200 M HNO3, 25.0 mL of 0.200 М HCООH, 25.0 mL of 0.200 M NaOH, 25.0 mL of 0.100 M Ba(OН)2, and 20.0 mL of 0.100 M KOH. Assuming the volume change during the mixing can be ignored. What is the pH of this solution? (Ka= 1.8 x 10-4 for HСООН, log2 =0.301, log3 = 0.477)
(A) 6.90
(B) 5.58
(C) 4.91
(D) 3.92
(E) 3.57

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統計： A(0), B(1), C(1), D(0), E(0) #3847789