According to laplace variation of speed of sound are

Options

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

Answer

To solve the question regarding the Laplace variation of the speed of sound, we need to analyze the different processes mentioned: isothermal, isochoric, adiabatic, and isobaric.

### Step-by-Step Solution:

1. **Understanding the Speed of Sound**: The speed of sound in a medium depends on the properties of that medium, particularly its temperature and the type of process through which sound travels.

2. **Isothermal Process**: In an isothermal process, the temperature remains constant. According to Newton's law, he initially assumed that sound travels through air in an isothermal process, which led to an incorrect calculation of the speed of sound (280 m/s instead of the actual 330 m/s).

3. **Isochoric Process**: In an isochoric process, the volume remains constant. This process does not apply to sound propagation, as sound involves compressions and rarefactions, which change the volume of the medium.

4. **Isobaric Process**: In an isobaric process, the pressure remains constant. Similar to the isochoric process, this does not accurately describe the behavior of sound waves, which involve changes in pressure.

5. **Adiabatic Process**: An adiabatic process is characterized by no heat exchange with the surroundings. When sound travels through a medium, the particles of the medium undergo compression and rarefaction. During compression (crest formation), the particles come closer together, increasing temperature due to collisions. During rarefaction (trough formation), the particles move apart, leading to a decrease in temperature. However, this process happens so quickly that there is no time for heat exchange with the surroundings, making it adiabatic.

6. **Conclusion**: Based on the analysis, the correct answer is that according to Laplace, the variation of the speed of sound occurs in an **adiabatic process**. This is because the temperature of the medium changes during the propagation of sound waves, and heat exchange does not occur.

### Final Answer:
The correct option according to Laplace is: **Adiabatic**.