Which of the following has highest entropy?

Options

A. Water
B. Graphite
C. Mercury
D. Hydrogen

Explanation

To determine which of the given substances has the highest entropy, we need to understand the concept of entropy in relation to the states of matter. Entropy is a measure of disorder or randomness in a system. The more disordered a system is, the higher its entropy.

### Step-by-Step Solution:

1. **Identify the States of Matter**:
- We have four options:
- A. Water (liquid)
- B. Graphite (solid)
- C. Mercury (solid)
- D. Hydrogen (gas)

2. **Analyze Each Substance**:
- **Graphite**: As a solid, the particles are tightly packed in a fixed structure, leading to low randomness and low entropy.
- **Mercury**: Also a solid at room temperature, similar to graphite, it has low entropy due to its ordered structure.
- **Water**: As a liquid, the molecules are more spaced out than in solids, allowing for more movement and therefore higher entropy than solids.
- **Hydrogen**: Being a gas, hydrogen molecules are far apart and move freely, which results in the highest level of disorder and thus the highest entropy among the options provided.

3. **Compare the Entropy Levels**:
- In general, the order of entropy from lowest to highest is: solid < liquid < gas.
- Therefore, comparing the substances:
- Graphite (solid) < Mercury (solid) < Water (liquid) < Hydrogen (gas).

4. **Conclusion**:
- Since hydrogen is a gas, it has the highest entropy among the given options.

### Final Answer:
The substance with the highest entropy is **D. Hydrogen**.