A.
It would be of great help if we knew what the object in question is, but if it is unknown, the best method is to freeze the item intact in its package by dry ice, and store it in the aircraft cabinet until landing.

As long as the object is frozen, no chemical reaction should happen. When handling dry ice, use heavy gloves. Never touch dry ice with bare hands. If the object is in plastic or glass bottles, wrap the plastic or glass bottles by towel, and apply dry ice over the towel. Do not let dry ice touch such package directly.