A certain liquid has been analyzed and demonstrated a pH change from 6 to 8. Choose the most appropriate indicator to detect this pH change based on the figure below.

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.

An unknown colorless solution turns red when paramethyl red is added. It turns orange when erythrosine is added. Choose another indicator that will give a more precise value for the pH of the solution

a. Metacresol Purple

b. Thymolphthalein

c. Quinaldine Red

d. Ethyl Red

An unknown solution turns blue when methyl green is added. It also turns blue when congo red is added. Which range of pH values could the solution be?

Consider the following situation:

A student was asked to titrate a weak acid with a strong base. The student then started slowly adding the strong base to a fixed amount of weak acid, however, he remembered that he didn't put the indicator. The indicator was supposed to change from colorless to pink when the titration is complete. The student then tried adding a prescribed amount of the indicator to the solution that they already started titrating. The solution did not change color and was still colorless. What should the student do next?