Among the following, which has the lowest enthalpy of fussion?

Options

A. Flourine
B. Hydrogen
C. Chlorine
D. Helium

Answer

To determine which substance has the lowest enthalpy of fusion among the given options, we need to understand the concept of enthalpy of fusion and the factors that influence it.

### Step-by-Step Solution:

1. **Understanding Enthalpy of Fusion**:
- Enthalpy of fusion (also known as latent heat of fusion) is the amount of energy required to change a substance from a solid to a liquid at constant pressure. This process involves breaking intermolecular forces in the solid state.

2. **Factors Affecting Enthalpy of Fusion**:
- The enthalpy of fusion is influenced by the strength of the intermolecular forces holding the solid together. Substances with weaker intermolecular forces generally have lower enthalpy of fusion, as less energy is needed to overcome these forces.

3. **Comparison of Substances**:
- To find the substance with the lowest enthalpy of fusion, we can compare the enthalpy values of different substances. In this case, we are particularly interested in helium, which is known for its unique properties.

4. **Helium’s Unique Properties**:
- Helium is a noble gas with a very low boiling point and enthalpy of fusion. It has a complete electron configuration (1s²), and its atoms are held together by very weak van der Waals forces. This means that it requires very little energy to change from solid to liquid.

5. **Conclusion**:
- Among the substances considered, helium has the lowest enthalpy of fusion due to its weak intermolecular forces and unique atomic structure. Therefore, the answer is helium.

### Final Answer:
Helium has the lowest enthalpy of fusion among the given options.

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