Farmers Who Raise Cotton Once Used Arsenic Acid,H₃AsO₄,as a Defoliant

question 121

Multiple Choice

Farmers who raise cotton once used arsenic acid,H₃AsO₄,as a defoliant at harvest time.Arsenic acid is a polyprotic acid with K_a1 = 2.5 × 10^-4,K_a2 = 5.6 × 10^-8,and K_a3 = 3 × 10^-13.What is the pH of a 0.500 M solution of arsenic acid?

• A)0.85
• B)1.95
• C)3.90
• D)4.51
• E)None of these choices is correct.