Final answer:
Undercooled nickel remains in a liquid state because it is at a temperature below its normal freezing point without solidification occurring.Option 2 is the correct answer. Undercooled liquid nickel remains in a 2) liquid state until a critical point initiates solidification.
Step-by-step explanation:
When a liquid nickel is undercooled, it remains in a liquid state but at a temperature below its normal freezing point. It has not transitioned to a solid state due to the lack of nucleation centers necessary for the solidification process to begin. Hence, the state of the undercooled nickel is liquid. Matter typically exists in one of three states: solid, liquid, or gas, and these different states have different properties. In the context of the question, the homogeneous undercooled nickel has not changed its state and therefore it is not a solid, gas, or plasma.
Undercooling refers to the process of cooling a substance below its usual freezing or melting point without it undergoing a phase transition. In the case of liquid nickel undercooling, the state remains 2) Liquid. Undercooling doesn't automatically trigger a change in state; instead, it retains the liquid phase until a critical point is reached, initiating solidification. Therefore, despite being undercooled, the nickel remains in a liquid state. This phenomenon is common in certain materials, and the transition to a solid state occurs when the undercooling reaches a threshold and triggers the formation of solid nuclei within the liquid.