The number of properties on which reduction potential depends is
1) Electron gain enthalpy
2) Sublimation enthalpy
3)Ionisation enthalpy
4)Hydration enthalpy

Answer

To determine the number of properties on which the reduction potential depends, we will analyze each of the given properties in relation to the reduction potential.

### Step-by-Step Solution:

1. **Understanding Reduction Potential**:
- Reduction potential (E°) is the tendency of a species to gain electrons and be reduced. It is influenced by various thermodynamic properties.

2. **Analyzing Each Property**:
- **Electron Gain Enthalpy**: This property refers to the energy change when an electron is added to a neutral atom in the gas phase. It is relevant for reduction processes but is not directly involved in the calculation of reduction potential.

- **Sublimation Enthalpy**: This is the energy required to convert a solid into a gas. In the context of reduction potential, sublimation enthalpy is important because it relates to the energy needed to convert the solid metal to gaseous atoms before ionization occurs.

- **Ionization Enthalpy**: This is the energy required to remove an electron from a gaseous atom. It is crucial for determining the reduction potential since it represents the energy needed to form cations from neutral atoms.

- **Hydration Enthalpy**: This is the energy released when gaseous ions are solvated in water. It is also significant in the reduction potential as it accounts for the stabilization of ions in solution.

3. **Applying the Born-Haber Cycle**:
- The Born-Haber cycle helps to visualize the energy changes involved in the formation of ions from solids. In this cycle:
- The sublimation enthalpy is used to convert the solid to gas.
- The ionization enthalpy is used to remove an electron from the gaseous atom.
- The hydration enthalpy is used to account for the energy released when the gaseous ion is solvated.

4. **Conclusion**:
- From the analysis, we find that:
- Sublimation enthalpy (2) is involved.
- Ionization enthalpy (3) is involved.
- Hydration enthalpy (4) is involved.
- Electron gain enthalpy (1) is not involved in this specific process.

Thus, the total number of properties on which the reduction potential depends is **3** (sublimation enthalpy, ionization enthalpy, and hydration enthalpy).

### Final Answer:
The number of properties on which reduction potential depends is **3**.