How many of the following physical properties are extensive:
(i) Free energy (ii) vapour pressure (iii) mole (iv) kinetic energy
(v) Entropy (vi) Internal energy (vii) Enthalpy (viii) specific heat capacity
(ix) Coefficient of viscosity

Explanation

To determine how many of the listed physical properties are extensive, we need to understand the difference between extensive and intensive properties:

- **Extensive properties** are those that depend on the amount of substance present. Examples include mass, volume, and total energy.
- **Intensive properties** are those that do not depend on the amount of substance present. Examples include temperature, pressure, and density.

Now, let's analyze each property listed in the question:

1. **Free Energy**:
- Free energy is an extensive property because it depends on the amount of substance present.

2. **Vapor Pressure**:
- Vapor pressure is an intensive property because it does not depend on the amount of substance; it is characteristic of the substance at a given temperature.

3. **Mole**:
- The mole is an extensive property as it directly relates to the amount of substance present.

4. **Kinetic Energy**:
- Kinetic energy is an extensive property because it depends on the mass of the substance.

5. **Entropy**:
- Entropy is an extensive property as it also depends on the amount of substance.

6. **Internal Energy**:
- Internal energy is an extensive property because it is proportional to the amount of substance.

7. **Enthalpy**:
- Enthalpy is an extensive property since it depends on the amount of substance.

8. **Specific Heat Capacity**:
- Specific heat capacity is an intensive property because it is defined per unit mass of the substance.

9. **Coefficient of Viscosity**:
- Coefficient of viscosity is an intensive property because it does not depend on the amount of substance.

Now, let's summarize the properties identified as extensive:

- Free Energy (Extensive)
- Mole (Extensive)
- Kinetic Energy (Extensive)
- Entropy (Extensive)
- Internal Energy (Extensive)
- Enthalpy (Extensive)

Total extensive properties = 6

### Final Answer:
There are **6 extensive properties** among the listed physical properties.