Suppose a 1 $\times$ 10^-6
B)9 $\times$ 10^-9
C)1 $\times$ 10^-6
D)6 $\times$ 10^-9
E)Insufficient Information Is Provided to Determine K_b

Suppose a 1.0 L solution containing 0.20 moles of morphine is titrated with 0.40 M HCl.The pH at the equivalence point is 4.543.What is the K_b of morphine?

A) 1.1 $\times$ 10^-6
B) 9.4 $\times$ 10^-9
C) 1.6 $\times$ 10^-6
D) 6.2 $\times$ 10^-9
E) Insufficient information is provided to determine K_b.