Speed of sound is maximum in:

Options

A. Water
B. Vacuum
C. Air
D. Iron

Explanation

To determine in which medium the speed of sound is maximum, we can analyze the properties of sound and how it travels through different states of matter.

### Step-by-Step Solution:

1. **Understanding Sound Waves**: Sound is a mechanical wave that requires a medium (solid, liquid, or gas) to travel. It cannot travel through a vacuum since there are no particles to transmit the sound.

2. **Mediums of Sound Propagation**: Sound travels through different mediums: solids, liquids, and gases. The speed of sound varies in these mediums due to their different physical properties.

3. **Comparison of Sound Speed in Different Mediums**:
- **Solids**: In solids, particles are closely packed together, allowing sound waves to transfer energy quickly from one particle to another. This results in a high speed of sound.
- **Liquids**: In liquids, particles are less tightly packed than in solids, but they are still closer than in gases. Therefore, sound travels faster in liquids than in gases but slower than in solids.
- **Gases**: In gases, particles are far apart, which makes the transfer of sound energy slower compared to solids and liquids.

4. **Conclusion**: Based on the properties of sound propagation in different states of matter, we can conclude that the speed of sound is maximum in solids, particularly in dense materials like iron.

### Final Answer:
The speed of sound is maximum in solids, with iron being one of the materials where sound travels the fastest.

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