Final answer:
A 0.10 M aqueous solution of Na₃PO₄ is basic due to the ionization of the weakly acidic anion PO₄³⁻, which can accept hydrogen ions, leading to an increased pH.
option a is the correct
Step-by-step explanation:
A 0.10 M aqueous solution of Na₃PO₄ will be basic. This is because Na₃PO₄ is a salt formed from the neutralization of a strong base, NaOH, and a weak acid, H₃PO₄.
When Na₃PO₄ dissolves in water, it dissociates into Na⁺ ions and PO₄³⁻ ions. Sodium ions (Na⁺) are considered inert, meaning they do not affect the pH of the solution significantly. On the other hand, PO₄³⁻ ions, which are the conjugate base of the weak acid HPO₄²⁻, can accept a hydrogen ion (H⁺) and increase the pH, making the solution basic.
The K₂ of HPO₄²⁻ (4.2 × 10⁻¹³) indicates that the ability to accept a proton is significant, leading to a higher concentration of OH⁻ ions in the solution. Therefore, since the ability to accept a proton (basic property) is stronger than the ability to donate a proton (acidic property), the solution is basic.