Answer:
B. Indicator
Step-by-step explanation:
An indicator is used to determine whether an acid or alkali has been added to a solution.
An acid or alkali changes the hydrogen ion concentration in solution. This is indicated by the pH of the solution after which the acid or alkali has been added.
- To see this change, indicators are used.
- An indicator employs color changes to show a change in chemical properties which pertains to the pH.
- There are several indicators used which are litmus paper, phenolphthalein, methyl orange