Equilibrium

10 mL of 0.1 N (0.1 M) NaOH = 10 0.1 = 1 millimole
10 mL of 0.05 N (0.025 M) H



0.25 millimole of H will react with
0.5 millimole of NaOH.
NaOH left= 1- 0.5 = 0.5 millimole
Volume of reaction mixture = 20 mL
Molarity of NaOH in mixture solution=