The point of dissimilarity between `(SO_(3) )_( 3)` and `(HPO_(3))_(3)` (cyclic trimer) is :-

Options

A. Both have six membered ring.
B. Both contain central atom in same hybridisation.
C. Both contain planar ring.
D. Both are isoelectronic

Answer

To determine the point of dissimilarity between \( (SO_3)_3 \) and \( (HPO_3)_3 \) (cyclic trimer), we will analyze their structures, hybridization, and other properties step by step.

### Step 1: Analyze the Structure of \( (SO_3)_3 \)
1. **Chemical Formula**: The cyclic trimer of sulfur trioxide is represented as \( S_3O_9 \).
2. **Structure**: Each sulfur atom is double bonded to an oxygen atom and is connected to two other sulfur atoms. The structure can be visualized as a cyclic arrangement of three sulfur atoms, each bonded to three oxygen atoms.

### Step 2: Analyze the Structure of \( (HPO_3)_3 \)
1. **Chemical Formula**: The cyclic trimer of phosphoric acid is represented as \( H_3P_3O_9 \).
2. **Structure**: Each phosphorus atom is bonded to one hydroxyl group (–OH) and is also connected to two other phosphorus atoms. The structure consists of three phosphorus atoms, each bonded to three oxygen atoms.

### Step 3: Compare the Rings
1. **Number of Members**: Both \( (SO_3)_3 \) and \( (HPO_3)_3 \) have six-membered rings.
- **Conclusion**: Both have six-membered rings, so this is not a point of dissimilarity.

### Step 4: Hybridization of Central Atoms
1. **Hybridization of Sulfur in \( (SO_3)_3 \)**: The central sulfur atom has four sigma bonds (three with oxygen and one with another sulfur), leading to \( sp^3 \) hybridization.
2. **Hybridization of Phosphorus in \( (HPO_3)_3 \)**: The central phosphorus atom also has four sigma bonds (three with oxygen and one with another phosphorus), leading to \( sp^3 \) hybridization.
- **Conclusion**: Both central atoms are \( sp^3 \) hybridized, so this is not a point of dissimilarity.

### Step 5: Planarity of the Rings
1. **Planarity of \( (SO_3)_3 \)**: The arrangement of oxygen atoms in \( (SO_3)_3 \) is not planar due to the presence of double bonds and the three-dimensional arrangement of sulfur atoms.
2. **Planarity of \( (HPO_3)_3 \)**: The presence of hydroxyl groups and the arrangement of phosphorus atoms also lead to a non-planar structure.
- **Conclusion**: Both structures are non-planar, but the arrangement of atoms leads to different spatial orientations.

### Step 6: Isoelectronic Nature
1. **Isoelectronic Species**: Both \( (SO_3)_3 \) and \( (HPO_3)_3 \) can be considered isoelectronic as they have the same number of total electrons (12 for each species).
- **Conclusion**: Both are isoelectronic species, so this is not a point of dissimilarity.

### Final Conclusion
The point of dissimilarity between \( (SO_3)_3 \) and \( (HPO_3)_3 \) is that they do not have planar rings, making option C the correct answer.