Final answer:
Sevoflurane is the inhaled anesthetic that is not stable in hydrated CO₂ absorbent, unlike Desflurane, Isoflurane, and Nitrous Oxide (N₂O).
Step-by-step explanation:
The inhaled anesthetic that is not stable in hydrated CO₂ absorbent is Sevoflurane. Sevoflurane can react with the CO₂ absorbent to produce compound A, which has been suggested to have nephrotoxic effects. Other inhaled anesthetics commonly used today include Desflurane, Isoflurane, and Nitrous Oxide (N₂O). These compounds are mostly less flammable and have fewer undesirable side effects compared to older anesthetics, yet it's important to consider their stability in different environments, such as with CO₂ absorbent materials used during surgeries.