How many milliliters of 0.100 M NaOH (aq) would be needed to completely neutralize 50.0 milliliters of 0.300 M HCl (aq) ?

(1) 16.7 mL (3) 150. mL

(2) 50.0 mL (4) 300. mL

The NaOH can react with HCl with the formula: NaOH + HCl = NaCl + H2O. So if you want to neutralize the solution, the molar number of NaOH and NCl need to be equal. So we need 0.3*50/0.1=150 milliliters.