Answer
$Na_3PO_4$ and $Na_2HPO_4$ are capable of forming a buffer solution.
Work Step by Step
1. For a buffer solution, we need:
- 1 Weak acid: $HP{O_4}^{2-}$
- 1 Weak base: ${PO_4}^{3-}$
2. They can't react with each other.
- Since they are a conjugate acid-base pair, that reaction will not happen.
Therefore, this pair can make a buffer solution.
