[Tom]

Which of these statements is not true of buffer solutions?

A buffer solution could consist of equal concentrations of ammonia and ammonium bromide.
   
A buffer solution could consist of equal concentrations of nitric acid, HNO3, and sodium nitrate.
   
A buffer solution will change only slightly in pH upon addition of acid or base.
   
In a buffer solution containing benzoic acid, C6H5COOH, and sodium benzoate, C6H5COONa, the species that reacts with added hydroxide ion is the benzoic acid.

[Mitch]

True: A buffer solution will change only slightly in pH upon addition of acid or base.

[Tom]

A buffer solution will resist change in ph when a moderate amount of an acid or base is added to it. A buffer solution consists of a weak acid and its conjugate base, or of a weak base and its conjucate acid.