Out of the following, choose the one which is not a part of internal energy?

Options

A. kinetic energy
B. potential energy
C. chemical bond energy
D. gravitational energy

Answer

To solve the question, "Out of the following, choose the one which is not a part of internal energy," we will analyze each option provided.

### Step 1: Understand Internal Energy
Internal energy is defined as the total energy contained within a system. It includes various forms of energy associated with the particles in the system, such as kinetic energy, potential energy, and energy associated with chemical bonds.

### Step 2: Analyze Each Option
1. **Kinetic Energy**: This is the energy of motion of the particles within a substance. It is a part of internal energy.

2. **Potential Energy**: This refers to the energy stored due to the position of particles in a system. It is also included in internal energy.

3. **Chemical Bond Energy**: This is the energy stored in the bonds between atoms in a molecule. This energy is part of internal energy.

4. **Gravitational Energy**: This energy arises due to the gravitational pull acting on the substance. It is not considered a part of the internal energy of a system.

### Step 3: Conclusion
From the analysis, we can conclude that:
- Kinetic energy, potential energy, and chemical bond energy are all components of internal energy.
- Gravitational energy is not a component of internal energy.

Thus, the correct answer is **option 4: gravitational energy**.