Which of the following isnot a strong electrolyte?

Options

A. NaCl
B. `KNO_(3)`
C. `NH_(4)OH`
D. `FeSO_(4)`

Answer

To determine which of the following compounds is not a strong electrolyte, we need to analyze each option based on their ability to ionize in solution.

### Step-by-Step Solution:

1. **Understand Strong Electrolytes**: Strong electrolytes are substances that completely dissociate into ions when dissolved in water. This means they ionize approximately 100%.

2. **Evaluate Each Option**:
- **Option 1: NaCl (Sodium Chloride)**
- When NaCl is dissolved in water, it dissociates completely into Na⁺ and Cl⁻ ions.
- **Conclusion**: NaCl is a strong electrolyte.

- **Option 2: KNO3 (Potassium Nitrate)**
- KNO3 also dissociates completely in water into K⁺ and NO3⁻ ions.
- **Conclusion**: KNO3 is a strong electrolyte.

- **Option 3: NH4OH (Ammonium Hydroxide)**
- NH4OH does not completely dissociate in water. It partially ionizes into NH4⁺ and OH⁻ ions.
- **Conclusion**: NH4OH is a weak electrolyte.

- **Option 4: FeSO4 (Iron(II) Sulfate)**
- FeSO4 dissociates completely into Fe²⁺ and SO4²⁻ ions in solution.
- **Conclusion**: FeSO4 is a strong electrolyte.

3. **Identify the Answer**:
- Among the options, NH4OH is the only compound that does not completely ionize in solution, making it the correct answer to the question.

### Final Answer:
**The compound that is not a strong electrolyte is NH4OH (Ammonium Hydroxide).**