Which one of the following statement is incorrect ?

Options

A. A solution containing non - volatile solute freezes at a lower temperature than the pure solvent
B. A solution constraining non - volatile solute boils at a higher temperature than the pure solvent
C. 0.1 M NaCl solution and 0.1 M sugar solution have the same boiling point
D. Osmosis cannot take place without a semi - permeable membrane

Answer

To solve the question of identifying the incorrect statement among the given options, we will analyze each statement step by step.

### Step 1: Analyze the First Statement
**Statement:** A solution containing a non-volatile solute freezes at a lower temperature than the pure solvent.

- **Explanation:** This statement is true. When a non-volatile solute is added to a solvent, the freezing point of the solution decreases compared to the pure solvent. This phenomenon is known as freezing point depression.

### Step 2: Analyze the Second Statement
**Statement:** A solution containing a non-volatile solute boils at a higher temperature than the pure solvent.

- **Explanation:** This statement is also true. The presence of a non-volatile solute raises the boiling point of the solution compared to the boiling point of the pure solvent. This is known as boiling point elevation.

### Step 3: Analyze the Third Statement
**Statement:** 0.1m NaCl solution and 0.1m sugar solution have the same boiling point. Both have the same elevation in boiling point.

- **Explanation:** This statement is false. The boiling point elevation depends on the van 't Hoff factor (i) and the molality (m) of the solution. For NaCl, which dissociates into two ions (Na⁺ and Cl⁻), the van 't Hoff factor (i) is 2. Therefore, the elevation in boiling point for the NaCl solution is greater than that for the sugar solution, which has a van 't Hoff factor of 1. Thus, the boiling points of these two solutions are not the same.

### Step 4: Analyze the Fourth Statement
**Statement:** Osmosis cannot take place without a permeable membrane.

- **Explanation:** This statement is true. Osmosis is defined as the movement of solvent molecules through a semi-permeable membrane from a region of lower solute concentration to a region of higher solute concentration. Without a semi-permeable membrane, osmosis cannot occur.

### Conclusion
After analyzing all the statements:
- The first statement is true.
- The second statement is true.
- The third statement is false (incorrect).
- The fourth statement is true.

Thus, the incorrect statement is the third one.

### Final Answer
The incorrect statement is: **0.1m NaCl solution and 0.1m sugar solution have the same boiling point.**

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