Final answer:
A CO2 extinguisher's discharge method is stored liquefied compressed gas. The behavior of CO2 in extinguishers changes with temperature, with liquid CO2 present below its critical temperature of 31 °C, and only gas present above this temperature.
Step-by-step explanation:
A carbon dioxide (CO2) extinguisher's means of discharge is B. stored liquefied compressed gas. This is because carbon dioxide can exist as a liquid at high pressures within a fire extinguisher. When a CO2 extinguisher is discharged, the high-pressure gas expands rapidly, cooling the temperature of the gas, which can turn some of it into snow-like particles.
The critical temperature of carbon dioxide is 304 K (31 °C). When the extinguisher is shaken on a cool day with temperatures below this critical point, liquid CO2 is present, causing a sloshing sound. On a hot day above the critical temperature, such as 35 °C, no liquid state can be formed regardless of the pressure, so no sloshing sound is heard when the extinguisher is shaken.
Understanding the behavior of CO2 at different temperatures is essential for handling and storage of CO2 fire extinguishers safely. This is particularly important because excessive heat can lead to an increase in internal pressure, potentially causing safety concerns.