Colloidal sulphur is obtained when

Options

A. sulphur is heated gradually to high temperature
B. sulphur is heated with dilute sulphuric acid
C. hydrogen sulphide is passed through an aqueous solution of nitric acid
D. sulphur is warned with carbon disulphide

Answer

To determine how colloidal sulfur is obtained, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**: We need to consider the reactants that can lead to the formation of colloidal sulfur. One common reactant is hydrogen sulfide (H₂S).

2. **Consider the Reaction with Nitric Acid**: When hydrogen sulfide (H₂S) reacts with nitric acid (HNO₃), it can lead to the formation of sulfur. The balanced chemical reaction is:
\[ 2 H₂S + 6 HNO₃ \rightarrow 2 S + 6 NO₂ + 4 H₂O \]
In this reaction, H₂S is oxidized, and sulfur is produced.

3. **Formation of Colloidal Sulfur**: The sulfur produced in this reaction can exist in a colloidal form. Colloidal sulfur is a fine dispersion of sulfur particles in a medium, which can occur under certain conditions.

4. **Examine the Options**: Now, let's analyze the options provided in the question:
- **Option 1**: Sulfur heated gradually to high temperature - This does not produce colloidal sulfur.
- **Option 2**: Sulfur heated with dilute sulfuric acid - This does not produce colloidal sulfur.
- **Option 3**: Hydrogen sulfide gas is passed through aqueous sulfuric acid - This can produce colloidal sulfur.
- **Option 4**: Sulfur warmed with carbon disulfide - This does not produce colloidal sulfur.

5. **Conclusion**: Based on the analysis, the correct answer is that colloidal sulfur is obtained when hydrogen sulfide gas is passed through aqueous sulfuric acid.

### Final Answer:
Colloidal sulfur is obtained when hydrogen sulfide gas is passed through aqueous sulfuric acid.