The indicator bromthymol blue was added in each of the solutions shown below. Solution A contains 0.020 M hydrocyanic acid. Solution B contains a mixture of 0.020 M hydrocyanic acid and 0.020 M sodium cyanide. Using the figures below as reference, identify the solution with the lower pH.

• A. Solution A has a lower pH.
• B. Solution B has a lower pH.

Answer: (A)