< b="" />Explanation: < />
When water freezes or melts, it undergoes a phase change from a liquid to a solid or vice versa. During this phase change, energy is either absorbed or released in the form of heat. The amount of energy absorbed or released is known as the heat of fusion.

< b="" />Heat of Fusion: < />
The heat of fusion is the amount of energy required to change a substance from a solid to a liquid or vice versa, without a change in temperature. For water, the heat of fusion is 80 calories per gram.

< b="" />Melting Process: < />
When 1 gram of ice at 0 degrees Celsius melts, it absorbs 80 calories of heat energy from its surroundings. This energy is used to break the intermolecular forces between the water molecules, allowing them to move freely and form a liquid.

< b="" />Freezing Process: < />
When 1 gram of water at 0 degrees Celsius freezes, it releases 80 calories of heat energy to its surroundings. This energy is released as the water molecules come together and form a solid structure, creating intermolecular forces.

< b="" />Significance of Heat of Fusion: < />
The heat of fusion is an important property of substances because it determines the amount of energy required for phase changes. This property is used in various applications, such as in refrigeration systems where heat is absorbed during the melting process and released during the freezing process.

< b="" />Conclusion: < />
In conclusion, when 1 gram of water freezes or melts, 80 calories of energy are absorbed or released, respectively. This heat of fusion is a unique property of water and plays a significant role in various natural and technological processes.

Understanding the question:
The question is asking about the amount of calories absorbed or released when 1 gram of water freezes or melts. This refers to the process of changing the state of water from a liquid to a solid (freezing) or from a solid to a liquid (melting). The options provided are a) 680, b) 550, c) 80, and d) 580.

Explanation:
Calories:
Calories are units of energy commonly used to measure the amount of energy contained in food or released during chemical reactions. In the context of this question, calories refer to the amount of energy absorbed or released during the phase change of water (freezing or melting).

Freezing and Melting:
When water freezes, it changes from a liquid state to a solid state, forming ice. When water melts, it changes from a solid state (ice) to a liquid state. During these phase changes, energy is either absorbed or released.

Latent Heat:
The energy absorbed or released during phase changes is known as latent heat. It is the energy required to change the state of a substance without changing its temperature. The latent heat of fusion refers to the energy absorbed or released during the phase change between solid and liquid states (melting or freezing).

Calories absorbed/released during freezing and melting:
When 1 gram of water freezes or melts, it absorbs or releases approximately 80 calories of energy. This means that 80 calories of energy are either absorbed from the surroundings during the melting process or released to the surroundings during the freezing process.

Therefore, option c) 80 is the correct answer.

Summary:
When 1 gram of water freezes or melts, it absorbs or releases approximately 80 calories of energy. This energy is known as latent heat and is associated with the phase change between the solid and liquid states of water.