Which of the following mixtures would made the most effective buffer?
a.....100. mL 5.0M HF/0.05M NaF
b....100. mL 0.05M HF/0.05M NaF
c....500. mL 5.0M HF/ 5.0M Nal
d....100. mL 5.0M HF/5.0M NaF
a.....100. mL 5.0M HF/0.05M NaF
b....100. mL 0.05M HF/0.05M NaF
c....500. mL 5.0M HF/ 5.0M Nal
d....100. mL 5.0M HF/5.0M NaF