The most unsysmmetrical and symmeterical systems are, respectively:

Options

A. Tertragonal, Cubic
B. triclinic , Cubic
C. Rhombohedral, Hexagonal
D. Orthohombic, Cubic

Answer

To solve the question regarding the most unsymmetrical and symmetrical crystal systems, we will analyze the properties of the given crystal systems step by step.

### Step-by-Step Solution:

1. **Understanding Crystal Systems**:
- Crystal systems are categorized based on the lengths of their edges and the angles between those edges. The seven crystal systems are cubic, tetragonal, orthorhombic, rhombohedral, monoclinic, triclinic, and hexagonal.

2. **Identifying Symmetrical Systems**:
- The most symmetrical crystal system is the **cubic system**. In this system:
- All edge lengths are equal: \( a = b = c \)
- All angles are equal and are 90 degrees: \( \alpha = \beta = \gamma = 90^\circ \)

3. **Identifying Unsymmetrical Systems**:
- The most unsymmetrical crystal system is the **triclinic system**. In this system:
- All edge lengths are unequal: \( a \neq b \neq c \)
- All angles are also unequal: \( \alpha \neq \beta \neq \gamma \)

4. **Comparing Other Systems**:
- **Tetragonal System**:
- Edge lengths: \( a = b \neq c \)
- Angles: \( \alpha = \beta = \gamma = 90^\circ \)
- This system is symmetrical but not the most symmetrical.
- **Orthorhombic System**:
- Edge lengths: \( a \neq b \neq c \)
- Angles: \( \alpha = \beta = \gamma = 90^\circ \)
- This system is also symmetrical but not the most symmetrical.
- **Rhombohedral and Hexagonal Systems**:
- Both have some equal edge lengths and angles, but they do not meet the criteria for being the most symmetrical or unsymmetrical.

5. **Conclusion**:
- After analyzing the properties of each crystal system, we conclude that the **triclinic system** is the most unsymmetrical, and the **cubic system** is the most symmetrical.

### Final Answer:
The most unsymmetrical and symmetrical systems are, respectively: **triclinic and cubic**.

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