Heather is doing an acid-base reaction. she has 25.00 ml of hydrochloric acid of unknown concentration in a flask. she wants to add a basic solution to the acid drop by drop, until all the acid has reacted. which tool would be best for adding the basic solution dropwise and for most precisely measuring the volume of solution added? a graduated cylinder an eye dropper a beaker a buret

A buret.  In the question, Heather is preforming a titration.  If you look up a picture of a buret on line you will notice that it has a little knob on the bottom to control how much liquid you put in.  This actually makes it very accurate since you can start to put very precise amounts of base into the solution when you're nearing the equivalence point in a titration.

I hope this is helpful.  Let me know in the comments if anything is unclear.

What? i don’t understand