In a double replacement reaction, how many milliliters of 6.0 M phosphorus acid solution would be needed to react exactly with 25.0g of pure solid sodium

Question

hydroxide? This is the last part of the question 

Answer 1

H₃PO₃(aq) + 3NaOH(s) ==> Na₃PO_3(aq) + 3H₂O(l)

25.0 g NaOH x 1 mole/40.0 g x 1 mole H₃PO₃/3 moles NaOH x 1 L/6 mole x 1000 ml/L =34.7 ml