The crystal system having the highest and the lowest symmetries respectively , are

Options

A. cubic and rhombohedral
B. cubic and triclinic
C. rhombohedral and monolinic
D. cubic and monoclinic

Answer

To solve the question regarding the crystal systems with the highest and lowest symmetries, we can follow these steps:

### Step 1: Understand the Crystal Systems
There are seven crystal systems based on their symmetry and geometry:
1. Cubic
2. Tetragonal
3. Orthorhombic
4. Rhombohedral
5. Hexagonal
6. Monoclinic
7. Triclinic

### Step 2: Identify Symmetry in Crystal Systems
- **Cubic System**: All three axes (a, b, c) are equal, and all angles (α, β, γ) are 90°. This system has the highest symmetry.
- **Triclinic System**: All three axes are unequal (a ≠ b ≠ c), and all angles are also unequal (α ≠ β ≠ γ). This system has the lowest symmetry.

### Step 3: Conclusion
From the analysis:
- The crystal system with the **highest symmetry** is the **Cubic** system.
- The crystal system with the **lowest symmetry** is the **Triclinic** system.

### Final Answer
The crystal system having the highest and the lowest symmetries respectively are:
- **Cubic** (highest symmetry)
- **Triclinic** (lowest symmetry)

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