In group II, Formqation of whichsh tarbidity on dilation with `H_(2)O` indicate `Sb^(3+)` .

Explanation

To determine which turbidity indicates the presence of antimony (Sb^3+) in group II, we can analyze the reaction of antimony chloride with water.

### Step-by-Step Solution:

1. **Identify the Compound**: The question refers to antimony in its +3 oxidation state, which is typically present as antimony chloride (SbCl3).

2. **Reaction with Water**: When antimony chloride (SbCl3) is diluted with water, it undergoes hydrolysis. The reaction can be represented as:
\[ \text{SbCl}_3 + \text{H}_2\text{O} \rightarrow \text{SbOCl} + 2\text{HCl} \]

3. **Formation of Turbidity**: The product of this reaction is antimony oxychloride (SbOCl), which is known to form an orange-colored precipitate. This orange turbidity is a key indicator of the presence of Sb^3+ ions.

4. **Comparison with Other Group II Elements**: In contrast, when bismuth chloride (BiCl3) is treated with water, it forms bismuth oxychloride (BiOCl), which results in a white turbidity. Thus, the white turbidity indicates the presence of Bi^3+ ions.

5. **Conclusion**: Therefore, the formation of an orange turbidity upon dilution with water indicates the presence of antimony (Sb^3+).

### Final Answer:
The formation of orange turbidity on dilution with H2O indicates the presence of Sb^3+ (antimony).

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