The possible structure (s) of monnthio-carbonate ion is :

Options

A.
B.
C.
D.

Answer

To determine the possible structures of the monothio-carbonate ion (which contains one sulfur atom in place of one oxygen atom in the carbonate ion), we will analyze the resonance structures and their stability.

### Step-by-Step Solution:

1. **Identify the Composition of Monothio-Carbonate Ion**:
The monothio-carbonate ion consists of one carbon atom (C), one sulfur atom (S), and three oxygen atoms (O). The general formula can be represented as \( CSO_3^{2-} \).

2. **Draw Possible Lewis Structures**:
We can draw several resonance structures for the monothio-carbonate ion. The structures will involve different placements of double bonds and negative charges among the atoms.

- **Structure A**: One double bond between carbon and one oxygen, with the other two oxygens carrying negative charges.
- **Structure B**: A double bond between carbon and sulfur, with one oxygen carrying a negative charge.
- **Structure C**: A double bond between carbon and sulfur, with two oxygens carrying negative charges.
- **Structure D**: A double bond between carbon and one oxygen, with the sulfur atom carrying a negative charge.

3. **Evaluate Stability of Each Structure**:
- **Structure A**: Has a negative charge on oxygen, which is stable because oxygen is more electronegative.
- **Structure B**: Has a double bond with sulfur and a negative charge on oxygen. Sulfur can accommodate more electrons due to its larger size, but the double bond with carbon may not be as stable.
- **Structure C**: Contains two negative charges on oxygen, which is less stable due to the high electron density on oxygen.
- **Structure D**: This structure has a double bond between carbon and oxygen, with sulfur carrying a negative charge. This is less stable due to the larger size of sulfur and the unfavorable charge distribution.

4. **Determine the Most Stable Structure**:
After evaluating the stability of each structure, we conclude that Structure A is the most stable because it places the negative charge on the more electronegative oxygen atoms, leading to a more favorable charge distribution.

### Final Answer:
The most stable structure of the monothio-carbonate ion is the one with a double bond between carbon and one oxygen, while the other two oxygens carry negative charges.