Identify the correct order of solubility of `Na_(2)S,CuS` and ZnS in aqueous solution

Options

A. `CuS gt ZnS gt Na_(2)S`
B. `ZnS gt Na_(2)S gt CuS`
C. `Na_(2)S gt CuS gt ZnS`
D. `Na_(2)S gt ZnS gt CuS`

Explanation

To determine the correct order of solubility of `Na2S`, `CuS`, and `ZnS` in aqueous solution, we need to analyze the ionic character of these compounds and the size of their respective cations.

### Step-by-Step Solution:

1. **Understanding Ionic Character**:
- The solubility of ionic compounds in water is influenced by their ionic character. Compounds with higher ionic character tend to be more soluble because they dissociate more readily in water.

2. **Identifying the Cations**:
- The compounds in question are:
- `Na2S` (sodium sulfide) with cation `Na+`
- `CuS` (copper(II) sulfide) with cation `Cu2+`
- `ZnS` (zinc sulfide) with cation `Zn2+`

3. **Comparing Cation Sizes**:
- The size of the cation is crucial because larger cations generally have a higher ionic character.
- Sodium (Na+) is a Group 1 element and has a larger ionic size compared to the d-block elements copper (Cu2+) and zinc (Zn2+).
- Between `Cu2+` and `Zn2+`, zinc is larger than copper due to the electron configuration and the screening effect.

4. **Order of Cation Size**:
- Based on the size of the cations:
- Na+ > Zn2+ > Cu2+
- This indicates that sodium has the largest ionic size, followed by zinc, and then copper.

5. **Determining Solubility Order**:
- Since larger cations lead to higher solubility, we can conclude the order of solubility:
- `Na2S` > `ZnS` > `CuS`
- Therefore, the correct order of solubility in aqueous solution is:
- **Na2S > ZnS > CuS**

### Final Answer:
The correct order of solubility of `Na2S`, `CuS`, and `ZnS` in aqueous solution is:
**Na2S > ZnS > CuS**