Explore

Practice Paper

Answer key

Prepared by: learnloophq@gmail.com

Last edited 25 days ago by Learn LoopHQ.

Chapter: 04. Mixtures Separations Of Mixtures

⁠

I. Multiple Choice Questions (MCQs)

c) Sugar

c) Homogeneous mixture

c) It is a pure substance.

c) Winnowing

d) Sublimation

b) Alum

c) Sedimentation

c) Filtrate

II. Fill in the Blanks

mixture

retain

heterogeneous

decantation

evaporation

chemically

magnetic

III. True/False Questions

False

True

False

IV. Explanations of Terms

Emulsion: An emulsion is a mixture of two or more liquid components that are immiscible, meaning they cannot be completely mixed together, often resulting in a cloudy or milky appearance.

⁠

V. Short Answer Questions

Why do mixtures not have definite properties?

Mixtures do not have definite properties because their components are present in variable proportions, which means changing the amount of each component can alter the mixture’s overall properties. Also, the components retain their individual properties, contributing to the variability.

Name the method you would use to separate sawdust from water and explain why.

I would use filtration to separate sawdust from water. This is because sawdust is an insoluble solid that is lighter than water, and it can be easily trapped by a filter medium, allowing the water to pass through.

How can you obtain pure water from tap water using a separation method?

You can obtain pure water (distilled water) from tap water using evaporation followed by condensation (though condensation is not detailed in chapter). By heating the tap water, the water evaporates into vapor, leaving behind the dissolved salts and impurities. If this water vapor is then collected and cooled, it condenses back into pure liquid water.

⁠

VI. Observation-Based Questions

What will you observe after several hours?

After several hours, the mud particles will settle down at the bottom of the glass, and a layer of clearer water will be visible above the settled mud.

What is the name of the process that occurs when the mud settles down?

The process that occurs when the mud settles down is called sedimentation.

If the mud particles were very light and did not settle easily, what substance could you add to help them settle faster?

If the mud particles were very light and did not settle easily, you could add alum (a chemical substance) to help them settle faster, a process known as loading.

⁠

VII. Differentiating Concepts/Processes

Differentiate between homogeneous and heterogeneous mixtures with an example for each.

Homogeneous Mixture: A mixture in which its components are uniformly mixed throughout, and individual components cannot be seen separately. An example is sugar completely dissolved in water, forming a clear sugar solution.

Heterogeneous Mixture: A mixture in which its components are not uniformly mixed and can be seen separately. An example is a mixture of sand and water, where the sand particles are visible and eventually settle at the bottom.

⁠

VIII. Long Answer

Imagine you have a mixture of sand, common salt, and iodine. Describe a step-by-step procedure to separate all three components. Explain the reason behind each step.

To separate a mixture of sand, common salt, and iodine, a multi-step procedure is required:

Sublimation: First, gently heat the mixture in a china dish covered with an inverted funnel (with a cotton plug). Iodine is a sublimable substance, so it will directly turn into vapor upon heating and then deposit as solid iodine crystals on the cooler inner surface of the funnel, leaving sand and common salt in the dish.

Dissolution: Next, add water to the remaining mixture of sand and common salt in the china dish and stir well. Common salt is soluble in water, so it will dissolve to form a salt solution, while sand is insoluble and will remain as solid particles.

Filtration: Pour the mixture of sand and salt solution through a filter paper in a funnel. The insoluble sand particles will be trapped on the filter paper as residue, separating them from the salt solution (filtrate) that passes through.

Evaporation: Finally, heat the collected salt solution (filtrate) in a china dish. The water will evaporate, leaving behind the pure common salt as a solid residue.

⁠

IX. Environmental Awareness / Everyday Use

A city is facing a shortage of clean drinking water. Explain how a new technology using graphene-based sieves might help solve this problem, based on what you’ve learned.

Based on what we’ve learned, graphene-based sieves offer a promising solution to water shortage by enabling the removal of salt from seawater. This technology acts as a very fine filter that can separate salt particles from water molecules. If this sieve can effectively and efficiently desalinate seawater, it means cities near oceans can convert abundant saltwater into clean, drinkable water, significantly increasing their fresh water supply and addressing the shortage.

Want to print your doc?
This is not the way.

Try clicking the ⋯ next to your doc name or using a keyboard shortcut (

CtrlP

) instead.