which of the following leads to redox reaction ?

Options

A. `AgNO_(3)+HCl`
B. `KOH+HCl`
C. `KI+Cl_(2)`
D. `NH_(3)+HCl`

Explanation

To determine which of the given reactions leads to a redox reaction, we need to analyze each reaction by completing it and checking the oxidation states of the elements involved. A redox reaction involves the transfer of electrons, which results in changes in oxidation states.

### Step-by-Step Solution:

1. **Identify the Reactions:**
- We have four reactions to analyze:
1. AgNO3 + HCl → AgCl + HNO3
2. KOH + HCl → KCl + H2O
3. KI + Cl2 → KCl + I2
4. NH3 + HCl → NH4Cl

2. **Analyze the First Reaction: AgNO3 + HCl → AgCl + HNO3**
- **Oxidation States:**
- Ag in AgNO3: +1
- Ag in AgCl: +1
- N in AgNO3: +5
- N in HNO3: +5
- **Conclusion:** No change in oxidation states. This is **not a redox reaction**.

3. **Analyze the Second Reaction: KOH + HCl → KCl + H2O**
- **Oxidation States:**
- K in KOH: +1
- K in KCl: +1
- Cl in HCl: -1
- Cl in KCl: -1
- O in KOH: -2
- H in H2O: +1
- **Conclusion:** No change in oxidation states. This is **not a redox reaction**.

4. **Analyze the Third Reaction: KI + Cl2 → KCl + I2**
- **Oxidation States:**
- K in KI: +1
- I in KI: -1
- Cl in Cl2: 0
- K in KCl: +1
- Cl in KCl: -1
- I in I2: 0
- **Changes:**
- Cl changes from 0 to -1 (reduction).
- I changes from -1 to 0 (oxidation).
- **Conclusion:** This reaction involves both oxidation and reduction. Thus, it is a **redox reaction**.

5. **Analyze the Fourth Reaction: NH3 + HCl → NH4Cl**
- **Oxidation States:**
- N in NH3: -3
- H in NH3: +1
- Cl in HCl: -1
- N in NH4Cl: -3
- H in NH4Cl: +1
- Cl in NH4Cl: -1
- **Conclusion:** No change in oxidation states. This is **not a redox reaction**.

6. **Final Conclusion:**
- The only reaction that leads to a redox reaction is the third one: **KI + Cl2 → KCl + I2**.