Which of the following aqueous solutions are good buffer systems?
a. 0.34 M calcium iodide + 0.22 M sodium iodide.
b. 0.27 M ammonia + 0.38 M ammonium nitrate.
c. 0.27 M nitric acid + 0.18 M sodium nitrate.
d. 0.18 M hydrofluoric acid + 0.14 M hydroiodic acid.
e. 0.14 M calcium hydroxide + 0.28 M calcium chloride.