A Buffer Solution with a PH of 4

Multiple Choice

A buffer solution with a pH of 4.31 is prepared with 1.0 M HC₂H₃O₂ and ________ M NaC₂H₃O₂. The Ka of HC₂H₃O₂ is 1.8 × 10^-5.

A) 0.37
B) 0.74
C) 4.2 × 10^-6
D) 8.8 × 10^-10
E) 0.18