Which of the following solutions are good buffer systems?

Question

I. 0.20M calcium hydroxide+0.20M calcium chloride

 

II. 0.35M+0.32M ammonium nitrate 

 

III. 0.10M hypochlorus acid+0.14M hydrobromic acid

 

IV. 0.33M barium iodide+0.27M sodium iodide 

 

V. 0.29M hydrochloric acid+0.19M sodium chloride

 

A. II, III, and IV

B. II and V

C. I and IV 

D. II

E. All would be good buffers

Answer 1

None of them are buffers (good or bad).  To be a buffer, you must have a weak acid or a weak base plus the salt of that weak acid or weak base.  None of the choices fit that description.  Unfortunately, I can't tell what number II is supposed to be because nothing follows the 0.35 M, but if it happened to be 0.35 M ammonia, then answer II would be a good buffer.  It would contain a weak base (ammonia) and the salt of that weak base (ammonium nitrate).