Final answer:
The correct answer to the student's question is halon, which is used in fire extinguishers to create an oxygen-deficient atmosphere and stop fires by interrupting the chemical reaction.
Step-by-step explanation:
The substance described in the question as a broom Freon that works by replacing oxygen, thus creating an oxygen-deficient atmosphere is halon. Halon is used in fire extinguishers to disrupt the chemical reaction of a fire, effectively smothering it by reducing the available oxygen. This is distinct from other substances like chlorofluorocarbons (CFCs) and carbon dioxide (CO2), both of which have been used as refrigerants but have different properties and environmental impacts. CFCs, including substances known as Freons, have been phased out due to their harmful effect on the ozone layer, while CO2 is emerging as a more environmentally friendly refrigerant option.