Which of the following acts as a solid lubricant ?

Options

A. `SnO_(2)`
B. White tin
C. ZnO
D. Graphite

Answer

To determine which of the given options acts as a solid lubricant, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Solid Lubricants**:
Solid lubricants, also known as dry lubricants, are materials that can reduce friction between two surfaces without the need for a liquid or oil. They are typically in a solid phase.

2. **Identify Common Solid Lubricants**:
The most common solid lubricants include:
- **Graphite**: Known for its layered structure, which allows the layers to slide over each other easily, reducing friction.
- **Molybdenum Disulfide (MoS2)**: Another well-known solid lubricant that also has a layered structure, providing excellent lubrication properties.

3. **Evaluate the Options**:
If the question provides multiple options, we need to evaluate each one to see if it is a known solid lubricant.
- If **Graphite** is one of the options, it is indeed a solid lubricant.
- If **Molybdenum Disulfide** is an option, it is also a solid lubricant.
- Other materials may not be classified as solid lubricants.

4. **Select the Correct Answer**:
Based on the identification of solid lubricants, if the options include graphite, then the correct answer would be graphite.

### Conclusion:
The correct answer to the question "Which of the following acts as a solid lubricant?" is **Graphite**.

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