Final answer:
The gas valve controls the amount of gas entering the Bunsen burner.
Step-by-step explanation:
The part of the Bunsen burner that controls the amount of gas entering the burner is the gas valve.
The gas valve is located at the base of the burner and is usually a cylindrical knob or valve that can be turned to adjust the flow of gas.
By opening the gas valve, more gas is allowed to enter the burner, increasing the size of the flame. By closing the gas valve, less gas enters the burner, resulting in a smaller flame.