In which of the following processes, heat is neither absorbed nor released by a system?

Options

A. isochoric
B. isothermal
C. adiabatic
D. isobaric

Explanation

To determine in which of the following processes heat is neither absorbed nor released by a system, we need to analyze the characteristics of various thermodynamic processes. The relevant processes to consider are isochoric, isothermal, adiabatic, and isobaric.

### Step-by-Step Solution:

1. **Understanding Isochoric Process**:
- In an isochoric process, the volume of the system remains constant.
- Since the volume does not change, no work is done on or by the system.
- However, heat can still be absorbed or released to maintain the temperature, so heat is not constant in this process.

2. **Understanding Isothermal Process**:
- In an isothermal process, the temperature of the system remains constant.
- For the temperature to remain constant, heat must be exchanged with the surroundings.
- If the system expands, it absorbs heat; if it compresses, it releases heat. Thus, heat is exchanged in this process.

3. **Understanding Adiabatic Process**:
- In an adiabatic process, there is no heat exchange with the surroundings.
- The system is perfectly insulated, meaning that no heat is absorbed or released.
- Any change in internal energy is due to work done on or by the system, not heat transfer.

4. **Understanding Isobaric Process**:
- In an isobaric process, the pressure of the system remains constant.
- Heat can be absorbed or released in order to maintain constant pressure while the volume may change. Thus, heat is exchanged in this process.

5. **Conclusion**:
- Among the processes analyzed, the adiabatic process is the only one where heat is neither absorbed nor released by the system.
- Therefore, the answer to the question is the **adiabatic process**.

### Final Answer:
The process in which heat is neither absorbed nor released by a system is the **adiabatic process**.