" Captain Kirk, of the Starship Enterprise, has been told by his superiors that only a chemist can be trusted with the combination to the safe containing the dilithium crystals that power the ship. The combination is the $pH$ of solution A described below, followed by the $pH$ of solution C. (Example: If the $pH$ of solution $A$ is 3.47 and that of solution $C$ is 8.15 , then the combination to the safe is 3-47-8-15). The chemist must determine the combination using only the information below (all solutions are at ${25}^{\circ }C$ ):
Solution A is $50.0mL$ of a $0.100M$ solution of the weak monoprotic acid HX.
Solution B is a $0.0500M$ solution of the salt $NaX$. It has a $pH$ of 10.02 .
Solution C is made by adding $15.0mL$ of $0.250M$ $KOH$ to solution $A$.
What is the combination to the safe?