Which of the following acids would be needed to combine with its potassium salt to produce a solution buffered at pH 5.00? Chlorous acid: pKa = 1.95 Nitrous acid: pKa = 3.34 Formic acid: pKa = 3.74 Acetic acid: pKa = 4.74 Hypochlorous acid: pKa = 7.54