1. Calculate the moles of HCl and NaOH:

* Moles of HCl: (0.1 mol/dm³) * (50 cm³ / 1000 cm³/dm³) = 0.005 moles

* Moles of NaOH: (0.05 mol/dm³) * (100 cm³ / 1000 cm³/dm³) = 0.005 moles

2. Determine the limiting reactant:

* HCl and NaOH react in a 1:1 ratio. Since we have equal moles of both, they will completely neutralize each other.

3. Calculate the concentration of excess reactant (which is none in this case):

* Since the reaction is complete, there is no excess HCl or NaOH left.

4. Calculate the pH:

* The solution will be neutral because all the acid and base have reacted.

* The pH of a neutral solution is 7.

Therefore, the pH of the mixture is 7.