The first law of thermodynamics is a statement of :

Options

A. conservation of heat
B. conservation of work
C. conservation of momentum
D. conservation of energy

Explanation

To solve the question regarding the first law of thermodynamics, we can break it down into a step-by-step explanation.

### Step-by-Step Solution:

1. **Understanding the First Law of Thermodynamics**: The first law of thermodynamics is a fundamental principle in physics that relates to energy conservation. It states that energy cannot be created or destroyed, only transformed from one form to another.

2. **Mathematical Representation**: The first law can be mathematically expressed as:
\[ Q = \Delta U + W \]
where:
- \( Q \) is the heat added to the system,
- \( \Delta U \) is the change in internal energy of the system,
- \( W \) is the work done by the system.

3. **Interpretation of the Equation**: This equation indicates that the total heat added to the system (\( Q \)) is equal to the sum of the change in internal energy (\( \Delta U \)) and the work done by the system (\( W \)). This means that any heat energy supplied to the system can either increase its internal energy or be used to do work.

4. **Conservation of Energy**: The essence of the first law is the conservation of energy. It implies that the energy supplied to a system will either increase its internal energy or be converted into work done by the system. Therefore, it emphasizes that energy is conserved in all processes.

5. **Conclusion**: The first law of thermodynamics is fundamentally a statement of the conservation of energy, which can be summarized as:
- Energy added to a system is either stored as internal energy or used to perform work.

### Final Answer:
The first law of thermodynamics is a statement of the conservation of energy.

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