Question

bunsen burner safety
the safety flame is the:
blue flame
yellow - orange flame
invisible flame

Explanation:

A yellow - orange Bunsen burner flame is a safety flame as it is easily visible, indicating that the burner is on. A blue flame is a hotter, more complete - combustion flame, and an invisible flame is extremely dangerous as one may not know the burner is on.

Answer:

Yellow-orange flame