Why dry ice acts as a refrigerant?

Explanation

### Step-by-Step Solution:

1. **Definition of Dry Ice**:
- Dry ice is the solid form of carbon dioxide (CO2). It is commonly used for refrigeration purposes.

2. **Sublimation Process**:
- Dry ice does not melt into a liquid when heated. Instead, it undergoes sublimation, which is the process where a solid transitions directly into a gas without passing through the liquid phase.

3. **Cooling Effect**:
- When dry ice sublimates, it absorbs heat from its surroundings. This absorption of heat results in a cooling effect, which is why it is used as a refrigerant.

4. **Applications**:
- Due to its ability to maintain low temperatures and absorb heat, dry ice is widely used in shipping perishable items, in laboratories, and for special effects in entertainment.

5. **Conclusion**:
- Therefore, dry ice acts as a refrigerant primarily due to its property of sublimation, which allows it to absorb heat efficiently as it transitions from solid to gas.