Which one of the following can shown optical isomerism ?

Options

A. `FeSO_(4).7H_2O`
B. `K_3[Cr(C_2O_4)_3]`
C. `K_3[Fe(CN)_6]`
D. `[Cr(NH_3)_6]Cl_3`

Answer

To determine which of the given compounds can show optical isomerism, we need to analyze each option based on the criteria for optical isomerism. Optical isomers (enantiomers) are compounds that have the same molecular formula but differ in the spatial arrangement of atoms, resulting in non-superimposable mirror images. A compound must lack any symmetry (such as a plane of symmetry) to exhibit optical isomerism.

### Step-by-Step Solution:

1. **Understanding Optical Isomerism**:
- Optical isomers are compounds that are mirror images of each other and cannot be superimposed. This typically occurs in chiral molecules, which lack symmetry.

2. **Analyzing Each Option**:
- **Option 1: FeSO4·7H2O (Green Vitriol)**:
- This compound is octahedral in structure due to the six water molecules coordinated to iron.
- The presence of symmetry (specifically, a plane of symmetry) means it cannot show optical isomerism.
- **Conclusion**: Does not show optical isomerism.

- **Option 2: K3[Cr(C2O4)3]**:
- This compound has chromium coordinated to three bidentate oxalate ligands, resulting in a coordination number of six.
- The arrangement lacks symmetry, making it possible to have non-superimposable mirror images.
- **Conclusion**: Can show optical isomerism.

- **Option 3: K3[Fe(CN)6]**:
- This is also an octahedral complex with six cyanide ligands.
- The presence of symmetry (multiple planes of symmetry) indicates it cannot show optical isomerism.
- **Conclusion**: Does not show optical isomerism.

- **Option 4: [Cr(NH3)6]Cl3**:
- This octahedral complex has six ammonia ligands coordinated to chromium.
- Similar to the previous case, it has symmetry and thus cannot exhibit optical isomerism.
- **Conclusion**: Does not show optical isomerism.

3. **Final Conclusion**:
- The only compound that can show optical isomerism is **Option 2: K3[Cr(C2O4)3]**.

### Answer:
**Option 2: K3[Cr(C2O4)3] can show optical isomerism.**