Question

10.00mL of 0.100mol/L HCl solution is add to 10.00mL of 0.100mol/L NaOH solution. what is the pH of the resulting solution?

Answer 1

You have 1 millimole HCl added to 1 millimole NaOH which exactly neutralizes each other to give you NaCl and H2O for which the pH is 7.0 (ignoring the activity coefficient corrections).