When two compounds `Acl_(3) and DCl_(3)` of two elements A and D are mixed together a compound `ADCl_(6)` is formed. Structural analysis showed that `DCl_(3)` is trigonal planar and `AC l_(3)` is trigonal pyramidal. If anion has see - saw shape then shape of cation formed is

Options

A. Linear
B. Bent
C. Pentagonal bipyramidal
D. Trigonal planar

Answer

To determine the shape of the cation formed when the compounds ACl₃ and DCl₃ are mixed to form ADCl₆, we can analyze the information given about the structures of ACl₃ and DCl₃, as well as the resulting compound.

### Step-by-Step Solution:

1. **Identify the Shapes of ACl₃ and DCl₃**:
- DCl₃ is described as trigonal planar. This indicates that D has three bond pairs and no lone pairs, which is typical of elements from the boron family (Group 13) that can form three covalent bonds.
- ACl₃ is described as trigonal pyramidal. This suggests that A has three bond pairs and one lone pair, characteristic of elements from the nitrogen family (Group 15).

2. **Determine the Electron Configuration**:
- For D (from DCl₃), being in the boron family, it has three valence electrons. Thus, it forms three bonds with chlorine.
- For A (from ACl₃), being in the nitrogen family, it has five valence electrons. With three bonds to chlorine and one lone pair, it has a total of four electron pairs (3 bond pairs + 1 lone pair).

3. **Analyze the Formation of ADCl₆**:
- When ACl₃ and DCl₃ combine, they can form the compound ADCl₆.
- The cation (AD) will consist of A and D, and the anion will consist of Cl⁻ ions.

4. **Determine the Shape of the Cation**:
- The anion (Cl⁻) is said to have a seesaw shape. This typically arises from a central atom with five electron pairs (four bond pairs and one lone pair).
- The cation AD will have to accommodate the bonding with the anion. Since D has three bonds and A has three bonds plus one lone pair, the cation will be influenced by the geometry of the anion.

5. **Determine the Hybridization of the Cation**:
- Since A has three bond pairs and one lone pair, it will undergo sp³ hybridization. However, when it loses one electron to form the cation, it will have four electrons left, resulting in two bond pairs and one lone pair.
- This configuration leads to a bent shape for the cation AD.

6. **Final Conclusion**:
- The shape of the cation formed (AD) when ACl₃ and DCl₃ combine to form ADCl₆ is **bent**.