To understand the correct answer to the question of why supercooled water is thermodynamically unstable and tends to freeze into ice spontaneously, we need to delve into the concepts of thermodynamics and the formation of ice.
Supercooled water is liquid water that remains in a liquid state even when its temperature is below the normal freezing point of 0°C (32°F). This occurs because, in the absence of impurities or nucleation sites, water can avoid forming ice crystals and remain liquid.
Thermodynamically, a supercooled state is considered unstable. This is because the water molecules are in a high-energy state compared to their more stable form, which is ice at this temperature. Given the slightest perturbation such as a shock, impurity, or even further cooling, the system will spontaneously shift to a lower energy state by forming ice, as ice is the stable phase at temperatures below the freezing point.
The correct answer is that supercooled water is unstable and tends to freeze into ice spontaneously. This occurs due to the thermodynamic drive to reach a lower energy state, which results in the water freezing into ice upon encountering any perturbation.