Find total number of reagnets which cann produce `I_(2)` from KI solution.
Conc. `H_(2)SO_(4)," "Hg(NO_(3))_(2)"solution, "CuSO_(4)" solution, Conc."H_(3)PO_(4)`,
`K_(2)Cr_(2)O_(7)//H^(+)," "Cl_2" Water, "Pb(CH_(3)COO)_(2)" solution, "Ca(OCl)Cl//H^(+)," "NaNO_(2)+dil.HCl`

Answer

To determine the total number of reagents that can produce iodine (I₂) from potassium iodide (KI) solution, we will analyze each reagent provided in the question step by step.

### Step-by-Step Solution:

1. **Concentrated H₂SO₄**:
- Reaction: KI + H₂SO₄ → K₂SO₄ + HI + I₂
- Conclusion: This reaction produces I₂. **(Produces I₂)**

2. **Hg(NO₃)₂**:
- Reaction: KI + Hg(NO₃)₂ → HgI₂ + KNO₃
- Conclusion: This reaction does not produce I₂. **(Does not produce I₂)**

3. **CuSO₄**:
- Reaction: KI + CuSO₄ → Cu₂I₂ + K₂SO₄ + I₂
- Conclusion: This reaction produces I₂. **(Produces I₂)**

4. **Concentrated H₃PO₄**:
- Reaction: KI + H₃PO₄ → No reaction
- Conclusion: This reaction does not produce I₂. **(Does not produce I₂)**

5. **K₂Cr₂O₇ in acidic medium (H⁺)**:
- Reaction: KI + K₂Cr₂O₇ + H⁺ → Cr³⁺ + I₂
- Conclusion: This reaction produces I₂. **(Produces I₂)**

6. **Cl₂ in water**:
- Reaction: KI + Cl₂ → I₂ + KCl
- Conclusion: This reaction produces I₂. **(Produces I₂)**

7. **Pb(CH₃COO)₂**:
- Reaction: KI + Pb(CH₃COO)₂ → PbI₂ + CH₃COOK
- Conclusion: This reaction does not produce I₂. **(Does not produce I₂)**

8. **Ca(OCl)₂ in acidic medium (H⁺)**:
- Reaction: KI + Ca(OCl)₂ → CaCl₂ + I₂
- Conclusion: This reaction produces I₂. **(Produces I₂)**

9. **NaNO₂ + dilute HCl**:
- Reaction: KI + NaNO₂ + HCl → KCl + NaCl + NO + I₂
- Conclusion: This reaction produces I₂. **(Produces I₂)**

### Summary of Findings:
- Reagents that produce I₂:
1. Concentrated H₂SO₄
2. CuSO₄
3. K₂Cr₂O₇ in acidic medium
4. Cl₂ in water
5. Ca(OCl)₂ in acidic medium
6. NaNO₂ + dilute HCl

- Total number of reagents that can produce I₂ from KI solution: **6**

### Final Answer:
The total number of reagents which can produce I₂ from KI solution is **6**.