How many mL of .48 M NaOH are needed to react with 2.00 moles of H3PO4?
Write the equation and balance it.
mols H3PO4 = given
Using the coefficients in the balanced equation, convert mols H3PO4 to mols NaOH.
Then M NaOH = mols/L. You know M and mols, solve for L and convert to mL.