What Molar Ratio of Acetic Acid to Sodium Acetate Is $\times$

Multiple Choice

What molar ratio of acetic acid to sodium acetate is required to create a buffer solution having a pH of 4.89 at 25°C? K_a for HC₂H₃O₂ is 1.8 $\times$ 10^-5.

A) 0.72
B) 1.4
C) 0.56
D) 2.0
E) 2.9