A crystal may have one or more planes and one or more axes of symmetry but it has:

Options

A. Two centre of symmetry
B. One centre of symmetry
C. No centre of symmetry
D. None of these

Answer

To solve the question regarding the symmetry in crystals, we need to understand the concepts of planes of symmetry, axes of symmetry, and the center of symmetry.

### Step-by-Step Solution:

1. **Understanding Symmetry in Crystals**:
- A crystal can exhibit various types of symmetry, including planes of symmetry and axes of symmetry.
- A plane of symmetry is an imaginary plane that divides the crystal into two mirror-image halves.
- An axis of symmetry is an imaginary line around which the crystal can be rotated to produce a configuration that looks the same as the original.

2. **Defining Center of Symmetry**:
- The center of symmetry (also known as the inversion center) is a specific point in the crystal structure.
- It is defined as a point such that for any point in the crystal, there is an identical point located directly opposite to it at an equal distance from the center.

3. **Analyzing the Number of Centers of Symmetry**:
- In a crystal, there can be multiple planes and axes of symmetry, but the center of symmetry is unique.
- This is because the center of symmetry must be equidistant from all corresponding points in all directions.

4. **Conclusion**:
- Therefore, regardless of how many planes or axes of symmetry a crystal may have, it will always have only **one center of symmetry**.

### Final Answer:
A crystal may have one or more planes and one or more axes of symmetry, but it has **only one center of symmetry**.

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