What is the pH of a buffer solution that is 0.10 M NH₃ and 0.10 M NH₄⁺? What is the pH if 12 mL of 0.20 M hydrochloric acid is added to 125 mL of buffer?
a) pH = 9.21; pH after addition = 8.74
b) pH = 8.74; pH after addition = 5.00
c) pH = 5.00; pH after addition = 4.32
d) pH = 4.32; pH after addition = 3.89
