Which one of the following forms a negativity charged sol?

Options

A. `Al_(2)O_(3).xH_(2)O`
B. `Cr_(2)O_(3).xH_(2)O`
C. `TiO_(2)`
D. `Cds`

Answer

To determine which of the given options forms a negatively charged sol, we need to analyze each compound in terms of the ions that are adsorbed onto their surfaces.

### Step-by-Step Solution:

1. **Understanding the Concept of Charged Sols**:
- A sol is a colloidal suspension where particles are dispersed in a medium. The charge of the sol is determined by the ions that are adsorbed onto the surface of the colloidal particles.

2. **Analyzing Each Option**:
- **AL2O3.xH2O**:
- In this compound, Al³⁺ ions are adsorbed onto the surface, leading to a positively charged sol.
- **CR2O3.xH2O**:
- Here, Cr³⁺ ions are adsorbed, resulting in a positively charged sol as well.
- **TI4O2**:
- This compound also adsorbs Ti⁴⁺ ions, which means it forms a positively charged sol.
- **Cadmium Sulphide (CdS)**:
- In this case, the S²⁻ ions are adsorbed onto the surface of the particles, leading to a negatively charged sol.

3. **Conclusion**:
- Among the given options, only cadmium sulphide (CdS) forms a negatively charged sol due to the adsorption of sulphide ions (S²⁻).

### Final Answer:
The correct option that forms a negatively charged sol is **Cadmium Sulphide (CdS)**.