The correct option is A 0.05 M
Molarity of the original NaOH solution V1= 1 M
Volume of the original NaOH solution M1 = 10 mL
Volume of the diluted NaOH solution V2= 100 mL
Molarity of the diluted NaOH solution M2 = V1M1V2=10×1100=0.1 M
The chemical reaction involved in the titration is,
NaOH+HCl→NaCl+H2O
Given,
Volume of the HCl solution required for the titration V3 = 20 mL
Let, the molarity of HCl solution be = M3
Thus, M2V2=M3V3
Molarity of the HCl solution M3 = V2M2V3
Molarity of HCl M3 = 10×0.120=0.05 M