Which of the following statements about buffers is true? Group of answer choices A buffer composed of a weak acid of pKa = 5 is stronger at pH 4 than at pH 6. At pH values lower than the pKa, the salt concentration is higher than that of the acid. The strongest buffers are those composed of strong acids and strong bases. The pH of a buffered solution remains constant (exactly the same) no matter how much acid or base is added to the solution. When pH = pKa, the weak acid and salt concentrations in a buffer are equal.