Answer:
Boiling chips or stones
A rubber stopper or cork
Explanation:
Boiling stones are quite useful in the chemistry laboratory because they ensure even boiling and prevent the solution from boiling over. These chips are made to be porous so that they allow solvent vapors to form in the air cavities.
A rubber stopper or cork prevents the boiling liquid from spilling over during boiling by securing the mouth of the flask.
