The example that demonstrates the reversibility of a chemical change is refreezing carbon dioxide gas into dry ice.
This process is physical in nature (not a chemical change) as it involves a physical transition from gas to solid. However, the context implies one of the examples is meant to illustrate a reversible process.
In contrast:
- Recharging batteries involves a chemical change that is reversible.
- The rotting of eggs is an irreversible chemical change.
- Dehydrating sugar water typically involves a physical change where water is removed, but the sugar would still remain even though it's changed.
Given the options, recharging batteries and refreezing carbon dioxide gas into dry ice can be seen as reversible processes. However, recharging batteries involves a more complex chemical change that is reversible. Therefore, the best answer is recharging batteries.