Statement-I: `1M` solution of Glauber's salt is isotonic with 1M solution of `KNO_(3)`.
Because
Statement-II: Solutions having same molar concentration of solute may or may not have same osmotic pressure.

Answer

To analyze the given statements, we need to understand the concepts of isotonic solutions and osmotic pressure.

### Step-by-Step Solution:

1. **Understanding the Compounds**:
- Glauber's salt is sodium sulfate decahydrate, represented as Na2SO4·10H2O. When it dissolves in water, it dissociates into 2 sodium ions (Na⁺) and 1 sulfate ion (SO₄²⁻). Therefore, the total number of particles produced from 1 mole of Glauber's salt is 3 (2 Na⁺ + 1 SO₄²⁻).
- KNO3 (potassium nitrate) dissociates into 1 potassium ion (K⁺) and 1 nitrate ion (NO₃⁻), producing a total of 2 particles from 1 mole of KNO3.

2. **Calculating Van't Hoff Factor (i)**:
- For Glauber's salt (Na2SO4), the Van't Hoff factor (i) is 3.
- For KNO3, the Van't Hoff factor (i) is 2.

3. **Isotonic Solutions**:
- Two solutions are said to be isotonic if they exert the same osmotic pressure. The osmotic pressure (π) can be calculated using the formula:
\[ \pi = i \cdot C \cdot R \cdot T \]
where:
- \(i\) = Van't Hoff factor
- \(C\) = molar concentration
- \(R\) = universal gas constant
- \(T\) = temperature in Kelvin

4. **Comparing Osmotic Pressures**:
- For the 1M solution of Glauber's salt:
\[ \pi_{Glauber's} = 3 \cdot 1 \cdot R \cdot T = 3RT \]
- For the 1M solution of KNO3:
\[ \pi_{KNO3} = 2 \cdot 1 \cdot R \cdot T = 2RT \]
- Since \(3RT \neq 2RT\), the osmotic pressures are different. Therefore, a 1M solution of Glauber's salt is **not isotonic** with a 1M solution of KNO3.

5. **Evaluating the Statements**:
- **Statement I**: "1M solution of Glauber's salt is isotonic with 1M solution of KNO3." - This statement is **false**.
- **Statement II**: "Solutions having the same molar concentration of solute may or may not have the same osmotic pressure." - This statement is **true** because osmotic pressure depends on the Van't Hoff factor, which can vary between different solutes.

### Conclusion:
- Statement I is false.
- Statement II is true.