Question

bunsen burner safety
how do you get a yellow flame?
air hole open, gas tap half open
air hole closed, gas tap fully open
gas tap off, collar open

Explanation:

A yellow - orange flame on a Bunsen burner is produced when there is incomplete combustion. This occurs when the air hole is closed, preventing sufficient oxygen from mixing with the gas. Thus, the gas burns incompletely. Also, the gas tap being fully open provides more fuel for the incomplete combustion process.

Answer:

Air hole closed, gas tap fully open