Textbook J9 part b

[Brian Diehl 2B]

Identify the salt that is produced from the acid-base neutralization reaction between (b) ammonia and phosphoric acid. Write the complete ionic equation.

Answer:
(NH₄)₃PO₄, ammonium phosphate
3NH₃ + 3H⁺ + PO₄^3- --> 3NH₄⁺ + PO₄^3-

Why is the weak acid H₃PO₄ completely ionized on the reactant side of the equation? Shouldn't it also remain intact like the other weak acids in parts a, c, and d? Or does its polyprotic nature affect the complete ionic equation in some way?

[Rhea Jain 2I]

I believe that both dissociate because both the acid and base are weak in this equation. That's also why water isn't a product, as compared to the other 3 problems.