Question

bunsen burner safety most important safety question: what must you check before lighting up the bunsen burner? gas tap is fully open air - hole is completely closed heat - proof mat is under the burner

Explanation:

Before lighting a Bunsen burner, it is crucial to ensure the air - hole is completely closed to prevent a large, unmanageable flame. A fully open gas tap before lighting can be dangerous as it may cause a gas leak or a large, sudden flame. A heat - proof mat under the burner is more of a general safety measure during use rather than a pre - lighting check.

Answer:

Air - hole is completely closed