Assuming the mass of 5% Acetic Acid is 1.0g/mL, what volume of acetic acid is required to neutralize 25.0mL of 0.10M NaOH?

You have to convert the acid to moles.

.05*1g/ml*volumeacid /molmassAceticAcid=25ml*.1

volumeacid= 2.5ml/.05 * molmassAceticAcid