In the titration method, the student adds the hydrochloric acid drop by drop until the indicator changes colour. Which piece of equipment should be used to add the hydrochloric acid drop by drop in step 4?

A burette is the standard piece of equipment used in a titration to add the titrant (in this case, hydrochloric acid). Its long, graduated scale allows for the precise measurement of the volume of liquid delivered, and the tap at the bottom provides fine control, enabling the liquid to be added drop by drop, which is essential for finding the exact endpoint of the reaction.