moles =concentrationx volume
moles of NaOH = 0.1 x 50.000 = 5
Then just do the same calculation for all of them until one of the equals 5.
when I had this exact same question e) 50.000ml of 0.100M, which was the answer
Molarity is defined as moles/liters. So the concentration of your solution (your answer) is 1 M. You have a one molar solution (mol/L).