Ms Diksha, a science teacher gave different substances to three students. One spatula full of copper sulphate was given to student 1, wheat flour was given to student 2 and ink was given to student 3. Each student added the given sample to water and stirred. Which of the following statements is incorrect about the mixtures prepared by them?

Options

A. Particles are not visible to the naked eye in case of mixtures obtained by student 1 and student 3.
B. The path of light becomes visible in case of mixture obtained by student 1.
C. When passed through filter paper, particles of mixture obtained by student 2 remain behind on the filter paper.
D. The particles of mixture obtained by student 3 are about 100 times bigger than those of the mixture obtained by student 1.

Explanation

To solve the question regarding the mixtures prepared by the three students, we need to analyze the substances they were given and the nature of the mixtures they created when added to water.

### Step-by-Step Solution:

1. **Identify the Substances**:
- Student 1 received **Copper Sulphate**.
- Student 2 received **Wheat Flour**.
- Student 3 received **Ink**.

2. **Determine the Nature of Each Mixture**:
- **Copper Sulphate in Water**:
- Copper sulphate is a soluble salt. When added to water, it dissolves completely, forming a **true solution**. In a true solution, the solute particles are less than 1 nanometer in size, and they do not scatter light.

- **Wheat Flour in Water**:
- Wheat flour does not dissolve in water. Instead, it forms a **suspension**. In a suspension, the particles are larger than 100 nanometers and will eventually settle at the bottom if left undisturbed.

- **Ink in Water**:
- Ink is typically a colloidal solution. When mixed with water, it forms a **colloidal solution** where the particle size is between 1 nanometer and 100 nanometers. Colloidal solutions can scatter light, which is known as the Tyndall effect.

3. **Evaluate the Statements**:
- **Statement about Copper Sulphate**: "The mixture is a true solution." (True)
- **Statement about Wheat Flour**: "The mixture is a suspension." (True)
- **Statement about Ink**: "The mixture is a colloidal solution." (True)
- **Statement about Light Path**: "The path of light becomes visible in the mixture obtained by student 1." (Incorrect - this is false because true solutions do not scatter light.)
- **Statement about Filtration**: "Particles of the mixture obtained by student 2 remain on the filter paper." (True)
- **Statement about Particle Size**: "Particles of the mixture obtained by student 3 are about 100 times bigger than those of student 1." (True)

4. **Conclusion**:
- The incorrect statement is: "The path of light becomes visible in the mixture obtained by student 1." This is false because the particles in a true solution are too small to scatter light.

### Final Answer:
The incorrect statement about the mixtures prepared by the students is: "The path of light becomes visible in the mixture obtained by student 1."

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