For graphite which is possible ?

Options

A. `a=b=c,alpha=beta=gamma=90^(@)`
B. `a=b!=c,alpha=beta=gamma=90^(@)`
C. `a=b!=c,alpha=beta=90^(@),gamma=120^(@)`
D. `a!=b!=c,alpha=beta=gamma=90^(@)`

Answer

To answer the question "For graphite which is possible?", we will analyze the structure of graphite in terms of its unit cell and lattice parameters.

### Step-by-Step Solution:

1. **Understanding Graphite Structure**:
- Graphite is a form of carbon that has a layered structure. Each layer consists of carbon atoms arranged in a hexagonal lattice.

2. **Identifying the Lattice Type**:
- The lattice structure of graphite is classified as a hexagonal close-packed (HCP) lattice. This means that the arrangement of atoms in the unit cell is hexagonal.

3. **Defining Unit Cell**:
- A unit cell is the smallest repeating unit in a crystal lattice that reflects the symmetry and structure of the entire lattice. For graphite, the unit cell is hexagonal.

4. **Lattice Parameters**:
- In the case of graphite, the lattice parameters are defined as follows:
- Axial lengths: \( a = b \neq c \)
- Axial angles: \( \alpha = \beta = 90^\circ \) and \( \gamma = 120^\circ \)

5. **Conclusion**:
- Based on the above analysis, the correct conditions for the lattice parameters of graphite are:
- \( a = b \) (the lengths of the sides of the hexagon are equal)
- \( c \) (the height of the hexagonal prism) is different from \( a \) and \( b \)
- Angles: \( \alpha = \beta = 90^\circ \) and \( \gamma = 120^\circ \)

Thus, the correct answer is that for graphite, the condition \( a = b \neq c \) is possible, along with the specified angles.