Question

why was the mass of the erlenmeyer flask determined before adding the aspirin tablet?
the mass of the erlenmeyer is need to calculate the volume of the flask.
the mass of the aspirin tablet equals the mass of the flask containing the aspirin minus the mass of the flask.
its good practice to weigh the glassware.

Explanation:

To find the mass of the aspirin tablet, we use the difference - in - mass method. By subtracting the mass of the empty Erlenmeyer flask from the mass of the flask with the aspirin tablet, we get the mass of the tablet itself.

Answer:

The mass of the aspirin tablet equals the mass of the flask containing the aspirin minus the mass of the flask.