Statement-I: When mercuric iodide(s) is added to the aqueous solution of `KI`, the freezing point is raised.
Because
Statement-II: `HgI_(2)` reacts with `KI` forming complex ion `[Hg]_(4)^(2-)`

Answer

To solve the given question, we need to analyze both statements and determine their correctness and the relationship between them.

### Step-by-Step Solution:

1. **Understanding Statement I**:
- Statement I claims that when mercuric iodide (HgI₂) is added to an aqueous solution of potassium iodide (KI), the freezing point of the solution is raised.
- In general, adding a solute to a solvent lowers the freezing point of the solution (freezing point depression). Therefore, if the freezing point is raised, it suggests that the addition of HgI₂ is somehow counteracting this effect.

**Hint**: Recall the colligative properties of solutions, particularly freezing point depression.

2. **Understanding Statement II**:
- Statement II states that HgI₂ reacts with KI to form a complex ion [Hg₄]²⁻.
- This reaction implies that the addition of KI leads to the formation of a complex, which could affect the number of particles in solution.

**Hint**: Consider how complex formation affects the number of solute particles in solution.

3. **Analyzing the Reaction**:
- When HgI₂ is added to KI, it forms a complex ion, which reduces the number of free ions in solution. The reaction can be represented as:
\[ HgI_2 + 2KI \rightarrow K_2[HgI_4] \]
- This results in fewer particles (ions) in the solution compared to the initial state where HgI₂ and KI are separate.

**Hint**: Think about how the number of particles influences the colligative properties.

4. **Effect on Freezing Point**:
- The freezing point depression is directly related to the number of solute particles in the solution. Since the formation of the complex ion reduces the number of free ions, the van't Hoff factor (i) decreases.
- The freezing point depression (ΔTf) is given by the formula:
\[ \Delta T_f = i \cdot K_f \cdot m \]
- A decrease in the van't Hoff factor (i) leads to a decrease in ΔTf, which means the freezing point of the solution will actually increase.

**Hint**: Remember that a decrease in the number of solute particles leads to a decrease in freezing point depression.

5. **Conclusion**:
- Statement I is true because the addition of HgI₂ leads to an increase in the freezing point due to the formation of the complex ion.
- Statement II is also true as it correctly explains the phenomenon described in Statement I.

### Final Answer:
- **Statement I**: True
- **Statement II**: True
- **Relationship**: Statement II is the correct explanation for Statement I.