Final answer:
The minimum size of a CO2 absorbent canister is 200 grams, as it is designed to decrease in mass as gaseous CO2 is absorbed and removed from the container.
Step-by-step explanation:
The minimum size of a CO2 absorbent canister is 200 grams. This is because as carbon dioxide is absorbed, the mass of the container and its contents would decrease as CO2 is a gaseous product and would leave the container. Canisters are designed to capture expired gases through processes like the Douglas bag method, where all the expired air is collected for analysis of O₂ and CO₂ content, which can then be used to calculate the rates of oxygen utilization and CO2 production.