CBSE Class 9 Science Exploring Mixtures and Their Separation (Class 9 NCERT New) Quiz 1

1. Why do suspended particles settle in muddy water over time but not in milk?

A Because muddy water contains larger particles that settle due to gravity, while milk has smaller particles that remain suspended. B Because milk particles are heavier than those in muddy water, so they float. C Because muddy water is denser than milk, so particles settle faster. D Because milk is a solid and muddy water is a liquid.

2. Evaporation is different from boiling in that:

A Evaporation occurs at any temperature, while boiling occurs at a specific temperature. B Evaporation happens only at high temperatures, while boiling happens at low temperatures. C Evaporation and boiling both occur only at the boiling point. D Evaporation is a rapid process, while boiling is a slow process.

3. Why do you see bright rays of sunlight when it passes through small gaps between the leaves of a dense tree?

A Because sunlight is scattered and diffracted as it passes through small gaps, creating bright rays. B Because the leaves absorb all the sunlight, leaving only bright rays. C Because sunlight is reflected off the leaves, forming bright rays. D Because the tree produces its own light, resulting in bright rays.

4. Is the mixture of oil and water homogeneous or heterogeneous? Can you think of some other heterogeneous mixtures?

A The mixture of oil and water is heterogeneous. Examples of other heterogeneous mixtures include sand and water, salad, and granite. B The mixture of oil and water is homogeneous. Examples of other homogeneous mixtures include sand and water, salad, and granite. C The mixture of oil and water is homogeneous. Examples of other homogeneous mixtures include salt water, air, and vinegar. D The mixture of oil and water is heterogeneous. Examples of other heterogeneous mixtures include salt water, air, and vinegar.

5. Are the particles visible in each mixture? Record your observations for: A. Salt and water B. Chalk powder and water C. Milk and water

A A. Salt and water: Particles are not visible. B. Chalk powder and water: Particles are visible. C. Milk and water: Particles are not clearly visible, but the mixture is not transparent. B A. Salt and water: Particles are visible. B. Chalk powder and water: Particles are not visible. C. Milk and water: Particles are clearly visible. C A. Salt and water: Particles are not visible. B. Chalk powder and water: Particles are not visible. C. Milk and water: Particles are not visible. D A. Salt and water: Particles are visible. B. Chalk powder and water: Particles are visible. C. Milk and water: Particles are not visible.

6. Direct the light from a laser pointer through the beakers containing the mixtures and observe it from the side of the beaker in a direction perpendicular to the laser beam. Record your observations for:

A A. Salt and water: The laser beam is not visible in the mixture. B. Chalk powder and water: The laser beam is visible as it scatters due to the particles. C. Milk and water: The laser beam is visible as it scatters due to the colloidal particles. B A. Salt and water: The laser beam is visible as it scatters due to the particles. B. Chalk powder and water: The laser beam is not visible in the mixture. C. Milk and water: The laser beam is not visible in the mixture. C A. Salt and water: The laser beam is visible as it scatters due to the colloidal particles. B. Chalk powder and water: The laser beam is not visible in the mixture. C. Milk and water: The laser beam is not visible in the mixture. D A. Salt and water: The laser beam is visible as it scatters due to the particles. B. Chalk powder and water: The laser beam is visible as it scatters due to the colloidal particles. C. Milk and water: The laser beam is not visible in the mixture.

7. Predict what you would observe in each of the beakers if you leave them undisturbed for a few minutes.

A A layer of sediment settles at the bottom of each beaker. B The contents of each beaker remain completely mixed. C The liquid in each beaker evaporates completely. D The beakers change color due to a chemical reaction.

8. Set up a filtration apparatus and filter each mixture separately. Is there any residue left on the filter paper?

A Yes, there is residue left on the filter paper. B No, there is no residue left on the filter paper. C The residue dissolves completely in the filtrate. D The filter paper changes color but no residue is left.

9. Based on your observations, these are the same types of mixtures or are they different?

A They are the same types of mixtures. B They are different types of mixtures. C They are neither the same nor different. D They are both homogeneous mixtures.

10. What is a solute?

A A solute is the substance that gets dissolved in a solution. B A solute is the substance that dissolves other substances in a solution. C A solute is the liquid part of a solution. D A solute is the substance that evaporates from a solution.