11. In a titration to determine the concentration of hydronium ions in a test solution, the test solution was titrated with a 0.250 mol/L sodium hydroxide solution. Using 40.0 mL of test
solution, an average of 10.5 mL of sodium hydroxide solution was used to reach the
endpoint.

Calculate the molar concentration of the hydronium ion in the test solution. (1 point)

A) .0456 mol/L

B) 0.556 mol/L

C) .0656 mol/L

D). 0625 mol/L