What is the ph of the final solution when 10 mL of HCl is completely neutralized with 11mL of 0.1M Na(OH)?
You need the molarity of HCl. You can take some liberties with the question in as much as it says completely neutralized. You can assume that you have 1 mL of 0.1M NaOH in excess which will be diluted to 0.10M x (1/21) = 0.00476
Then pOH = -log(OH^-), find pH from
pH + pOH = pKw = 14.0