Which of the following represents the fully protonated form of a triprotic acid?

How does the relationship between K_a and K_b help in understanding polyprotic acids?

Which form of the Henderson-Hasselbalch equation should be used for a solution containing H₃A and H₂A-?

How does using moles instead of molarity affect the calculation of pH in the Henderson-Hasselbalch equation?

What is the effect of adding an acidic hydrogen to a polyprotic buffer?