On the basis of unit cell concept a crystal has :

Options

A. 7 systems
B. 14 systems
C. 230 systems
D. 32 systems

Answer

To solve the question regarding the classification of crystals based on the unit cell concept, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Unit Cell**:
- A unit cell is the smallest repeating unit in a crystal lattice that reflects the symmetry and structure of the entire crystal. It is defined by its dimensions and the arrangement of atoms within it.

2. **Identifying Crystal Systems**:
- Crystals can be classified into different systems based on the unit cell parameters (lengths of edges and angles between them). There are seven distinct crystal systems:
1. **Cubic**
2. **Tetragonal**
3. **Orthorhombic**
4. **Hexagonal**
5. **Rhombohedral (Trigonal)**
6. **Monoclinic**
7. **Triclinic**

3. **Analyzing the Options**:
- The question provides four options:
- 7th system
- 14th system
- 230 system
- 32 system
- We need to determine which of these options correctly corresponds to the classification of crystals based on the unit cell concept.

4. **Evaluating the Options**:
- The correct classification of crystal systems is based on the seven systems mentioned above.
- The terms "14th system," "230 system," and "32 system" do not correspond to the standard classification of crystal systems.
- The only relevant option that aligns with the classification of crystals based on unit cells is the "7th system."

5. **Conclusion**:
- Therefore, the correct answer is the **7th system**, which refers to the seven crystal systems based on the unit cell concept.

### Final Answer:
The crystal has a **7th system** based on the unit cell concept.

---