Choose the response that includes all the following combinations that are buffer solutions and none that are not buffer solutions. All components are present in 0.10 M concentrations.
I. HCN and NaCN
II. NH3 and NH4Cl
III. HNO3 and NH4NO3
IV. H2SO4 and Na2SO4
a. I, III, and IV
b. I and II
c. II, III, and IV
d. III and IV
e. I and III
Answer: B