A Popular Buffer Solution Consists of Carbonate (CO₃²¯) and Hydrogen

Multiple Choice

A popular buffer solution consists of carbonate (CO₃²¯) and hydrogen carbonate (HCO₃¯) conjugate acid-base pair. Which, if any, of the following such buffers has the highest buffer capacity?

A) 0.9 M CO₃²¯ and 0.1 M HCO₃¯
B) 0.1 M CO₃²¯ and 0.9 M HCO₃¯
C) 0.5 M CO₃²¯ and 0.5 M HCO₃¯
D) 0.1 M CO₃²¯ and 0.1 M HCO₃¯
E) They all have the same buffer capacity.