System and surroundings together constitute

Options

A. The earth
B. The solar system
C. Galaxy
D. Universe

Answer

To solve the question "System and surroundings together constitute," we need to understand the definitions of a system and its surroundings in thermodynamics.

### Step-by-Step Solution:

1. **Define the System**:
- A system is defined as the part of the universe that is being studied. It has fixed boundaries, which can be real (like a container) or imaginary (like a defined area in space).
- **Hint**: Remember that a system is what you focus on in your study.

2. **Define the Surroundings**:
- The surroundings refer to everything in the universe that is not part of the system. It includes all the external factors that can interact with the system.
- **Hint**: Surroundings are everything outside the system.

3. **Relationship Between System and Surroundings**:
- Together, the system and the surroundings encompass everything in the universe. They are interdependent, as the system can exchange energy and matter with its surroundings.
- **Hint**: Think of the system and surroundings as a complete picture of the universe.

4. **Identify the Correct Answer**:
- Given the options: Earth, solar system, galaxy, universe, the correct answer is that the system and surroundings together constitute the universe.
- **Hint**: The universe is the largest entity that includes everything, including both the system and its surroundings.

### Conclusion:
Thus, the answer to the question is that the system and surroundings together constitute the **universe**.