The correct option for the question is **C. regelation**. ### Explanation of the Correct Answer (C. Regelation) **Regelation** is a process that occurs when ice melts under pressure and then refreezes when the pressure is removed. In the scenario described, a thin wire with heavy weights is hung over a block of ice. When the wire is pulled down, it exerts pressure on the ice directly beneath it. This pressure causes the ice to melt at the point of contact with the wire, creating a thin layer of water. As the wire continues to cut through the ice, the water can flow away, and when the pressure is removed (as the wire moves or the weight is adjusted), the water refreezes, allowing the ice block to remain solid behind the wire. #### Step-by-Step Breakdown of the Process: 1. **Initial Setup**: A block of ice is resting on two supports, and a wire with heavy weights is placed over it. 2. **Application of Pressure**: The weight of the wire creates a significant downward force on the ice at the point of contact. 3. **Melting of Ice**: The pressure from the wire lowers the melting point of ice at that specific point, causing it to melt and form a thin layer of water. 4. **Movement of Wire**: As the wire cuts through the ice, the water created can flow away from the point of contact. 5. **Removal of Pressure**: If the pressure is reduced (for example, if the weight is lifted slightly), the water can refreeze, solidifying the ice behind the wire. 6. **Result**: The wire can effectively cut through the ice without the entire block melting, demonstrating the phenomenon of regelation. ### Why the Other Options are Incorrect: - **A. Condensation**: This is the process where gas turns into liquid. In this scenario, we are dealing with ice (solid) and water (liquid), not gas. Therefore, condensation does not apply here. - **B. Sublimation**: This is the process where a solid turns directly into a gas without passing through the liquid phase. While sublimation can occur with ice (turning into water vapor), it does not describe the process of cutting through ice with a wire. Thus, it is not relevant to the scenario. - **D. Fusion**: This term refers to the process of melting, where a solid turns into a liquid. While melting does occur in the ice under pressure, the specific process described in the question—where the ice melts and then refreezes—is more accurately described as regelation, not just fusion. ### Common Pitfalls: - **Confusing Melting with Regelation**: Students may think that melting (fusion) is the same as regelation. However, regelation specifically involves the melting under pressure and subsequent refreezing, which is a unique process. - **Overlooking Pressure Effects**: It's important to remember that the application of pressure changes the melting point of ice, which is a key aspect of regelation. ### Revision Summary: - **Regelation** is the process where ice melts under pressure and refreezes when the pressure is removed. - The scenario involves a wire cutting through ice due to the pressure exerted by weights. - Other options (condensation, sublimation, fusion) do not accurately describe the process occurring in the question. - Understanding the effects of pressure on melting points is crucial for grasping the concept of regelation.