It would be correct to use formula that says M_{acid}.V_{acid}=M_{base}.V_{base} at equivalence point of a titration between H_{3}PO_{4} and NaOH.
H_{3}PO_{4} is a weak acid and NaOH is a strong base. And the given formula is valid for the calculation of equivalence point of weak acid and strong base titration.
3. Would it be correct to use formula that says Macid Vacid = Mbase. V base at the equivalence point of a titration...