Answer:
B. Indicator
Step-by-step explanation:
An indicator is used to determine whether an acid or alkali has been added to a solution.
Indicators can be liquid or a paper called litmus paper. There also some digital forms of indicators that can tell whether an acid or alkali has been added to a solution.
- An acid and alkali will change the pH of a solution.
- pH is the amount of hydrogen ions that are in a solution
- So, these changes in the pH when an acid or alkali is introduced is usually monitored using indicators.
- Examples of indicators are litmus paper, methyl orange, methyl red, bromothymoblue