Which of the following mixtures would result in a buffered solution when 1.0 L of each of the two solutions are mixed?
a. 0.2 M HNO₃ and 0.4 M NaNO₃
b. 0.2 MHNO₃ and 0.4 M HF
c. 0.2 M HNO₃ and 0.4 M NaF
d. 0.2 M HNO₃ and 0.4 M NaOH