Among the following, the chiral complex is :

Options

A. `[Cr(OX)_(3)]^(3-)`
B. `cis-[PtCl_(2)(en)]`
C. `cis-[RhCl_(2)(NH_(3))_(4)]^(+)`
D. `trans-[PtCl_(2)(en)]`

Answer

To determine which of the given complexes is chiral, we need to analyze each complex for the presence of a plane of symmetry. A complex is considered chiral if it does not have a plane of symmetry, making it optically active.

### Step-by-Step Solution:

1. **Identify the complexes**: We need to analyze the given complexes for chirality. The complexes mentioned are:
- Option 1: Cr(ox)3
- Option 2: cis-[PtCl2(en)]
- Option 3: trans-[PtCl2(en)]
- Option 4: [PtCl2(en)2]

2. **Analyze Option 1: Cr(ox)3**:
- The oxalate ion (ox) is a bidentate ligand, meaning it forms two bonds with the central metal ion (Cr).
- When we visualize the structure of Cr(ox)3, we find that there is no plane that can divide the complex into two symmetrical halves.
- Therefore, Cr(ox)3 does not have a plane of symmetry and is considered chiral.

3. **Analyze Option 2: cis-[PtCl2(en)]**:
- In this complex, the two Cl ligands are on the same side (cis configuration).
- If we draw a plane through the center of the complex, this plane will pass between the two Cl ligands, dividing the complex into two symmetrical halves.
- Thus, this complex has a plane of symmetry and is not chiral.

4. **Analyze Option 3: trans-[PtCl2(en)]**:
- In the trans configuration, the two Cl ligands are opposite each other.
- A plane can also be drawn through the complex that separates the two Cl ligands, leading to symmetry.
- Therefore, this complex also has a plane of symmetry and is not chiral.

5. **Analyze Option 4: [PtCl2(en)2]**:
- In this complex, we have two bidentate ethylenediamine (en) ligands and two Cl ligands.
- Similar to the previous cases, a plane can be drawn that separates the Cl ligands, indicating the presence of symmetry.
- Hence, this complex is also not chiral.

6. **Conclusion**:
- After analyzing all options, we find that only **Option 1: Cr(ox)3** is chiral because it does not have a plane of symmetry.

### Final Answer:
The chiral complex is **Option 1: Cr(ox)3**.