Which of the followig is extensive variable?

Options

A. Internal energy
B. Temperature
C. Pressure
D. Density

Answer

To determine which of the following is an extensive variable among the options provided (internal energy, temperature, pressure, and density), we can follow these steps:

### Step-by-Step Solution:

1. **Define Extensive and Intensive Properties**:
- Extensive properties are physical quantities that depend on the size or amount of material in the system. Examples include mass, volume, and internal energy.
- Intensive properties are independent of the amount of material in the system. Examples include temperature, pressure, and density.

2. **Analyze Each Option**:
- **Internal Energy**: This is the total energy contained within a system. It is proportional to the number of particles or moles in the system. Therefore, it is an extensive property.
- **Temperature**: This is a measure of the average kinetic energy of the particles in a system. It does not depend on the size of the system, making it an intensive property.
- **Pressure**: This is defined as force per unit area. Since it is derived from the ratio of two extensive properties (force and area), it is also an intensive property.
- **Density**: This is defined as mass per unit volume. While it involves mass (an extensive property), it is a ratio and does not depend on the size of the system. Thus, it is an intensive property.

3. **Conclusion**:
- Among the options provided, the only extensive variable is **internal energy**.

### Final Answer:
The extensive variable is **internal energy**.

---