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 of a crystal, 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**:
- Crystals can exhibit various types of symmetry, including planes of symmetry and axes of symmetry. A plane of symmetry divides the crystal into two mirror-image halves, while an axis of symmetry allows for rotation of the crystal around a certain line, resulting in an identical appearance at certain angles.

2. **Defining Center of Symmetry**:
- The center of symmetry, also known as the inversion center, is a specific point in the crystal. For any point in the crystal, there is an equivalent point directly opposite to it, equidistant from the center of symmetry. This means that if you were to draw a line from any point on the crystal through the center of symmetry, you would find another identical point on the opposite side.

3. **Analyzing the Given Statement**:
- The question states that a crystal may have one or more planes and one or more axes of symmetry, but it has a specific characteristic regarding the center of symmetry.

4. **Conclusion**:
- Based on the definitions and properties of symmetry in crystals, we conclude that a crystal has **one center of symmetry**. This is a unique point that is consistent across the entire crystal structure.

5. **Final Answer**:
- Therefore, the answer to the question is: **One center of symmetry** (Option 2).