9th Standard Science Guide Matter Around Us Book Back Answers in English

Lesson 10 Matter Around Us

9th Science Guide: In this post, we will explore the book back answers for Lesson 10 on the Matter Around Us. This 9th science Matter Around Us Book Back Answers post takes you on a journey to understand the different types of matter, how they can be separated, and the properties of mixtures and pure substances.

Matter Around Us Book Back Answers

With the help of interesting questions and answers, learn about the distinctive qualities of compounds and pure substances. Test your knowledge with fun questions and answers, and dive into concepts like filtering, settling, compounds, and mixtures.

I. Choose the Correct Answer:

1. The separation of denser particles from lighter particles done by rotation at high speed is called _________

1. Filtration
2. sedimentation
3. decantation
4. centrifugation

Ans: Juice

2. Among the following _________ is a mixture

1. Common Salt
2. Juice
3. Carbon dioxide
4. Pure Silver

Ans: Juice

3. When we mix a drop of ink in water we get a _________

1. Heterogeneous Mixture
2. Compound
3. Homogeneous Mixture
4. Suspension

Ans: Homogeneous Mixture

3. When we mix a drop of ink in water we get a ___________

1. Heterogeneous Mixture
2. Homogeneous Mixture
3. Compound
4. Suspension

Ans: Homogeneous Mixture

4. _________ is essential to perform separation by solvent extraction method.

1. Separating funnel
2. filter paper
3. centrifuge machine
4. sieve

Ans: Separating funnel

5. __________ has the same properties throughout the sample

1. Pure substance
2. Mixture
3. Colloid
4. Suspension

Ans: Pure substance

6. The physical state of water at 373 K is _____________

1. Solid
2. liquid
3. vapour
4. plasma

Ans: vapour

7. The constituents that form a mixture are also called

1. Elements
2. Compounds
3. Alloys
4. Components

Ans: Components

II. State whether the following statements are True or False. If false give the correct statement.

1. Oil and water are immiscible with each other.

Ans: Ture

2. A compound cannot be broken into simpler substances chemically.

Ans: False

Correct Ans : A compound can be broken into simpler substances chemically.

3. Liquid–liquid colloids are called gel.

Ans: False

Correct Ans: Liquid – solid colloids are called gel.

4. Buttermilk is an example of heterogeneous mixture.

Ans: Ture

5. Aspirin is composed of 60% Carbon, 4.5% Hydrogen and 35.5% Oxygen by mass. Aspirin is a mixture.

Ans: False
Correct Ans: Aspirin is a compound.

6. Liquids expand more than gases on heating.

Ans: False

Correct Ans: Gases expand considerably on heating.

7. Water has a definite boiling point and freezing point.

Ans: Ture

III. A. Match the Following

IV. Fill in the Blanks

1. A _______ mixture has no distinguishable boundary between its components.

Ans: homogeneous

2. An example of a substance that sublimes is _______

Ans: naphthalene

3. Alcohol can be separated from water by _______

Ans: fractional distillation

4. In petroleum refining, the method of separation used is _______

Ans: fractional distillation

5. Chromatography is based on the principle of _______

Ans: different solubilities in the same solvent

6. Evaporation is always accompanied by _______ in temperature.

Ans: decrease

7. 150^oC = _______ K

Ans: 423

5. Latent heat is the energy used for _______

Ans: Inter conversion of matter

V. Short Answer

1. Differentiate between absorption and adsorption.

2. Define sublimation?

The process of conversion of matter from solid state directly into vapour state (without going to liquid state).

3. A few drops of ‘dettol’ when added to water the mixture turns turbid. Why?

The oil droplets of dettol get suspended in water and create an emulsion.

4. Name the apparatus that you will use to separate the components of mixtures containing two,

i) miscible liquids

fractional distillation

ii) immiscible liquids.

Separating funnel

5. Name the components in each of the following mixtures.

i. Ice cream, ii. Lemonade, iii. Air, iv. Soil

6. Why is it possible to row a boat in water but not pass through a wooden fence.

There are gaps between the molecules of water.

7. How does gaseous pressure arise?

The rapid motion and collision of molecules with the walls of the container causes pressure.

8. Which state of matter has the highest kinetic energy?

The gaseous state of matter.

VI. Short Answer

1. Which of the following are pure substances? Ice, Milk, Iron, Hydrochloric acid, Mercury, Brick and water

Iron (Fe), Hydrochloric acid (HCl), Mercury(Hg) and water (H₂o)

2. Oxygen is very essential for us to live. If forms 21% of air by volume. Is it at element or compound?

Oxygen is an element.

3. You have just won a medal made of 24-carat gold. Have you just procured a pure substance or an impure substance?

22-carat gold metal is made up of 91.6% gold (Au) and 8.4% other metals.

4. How will you separate a mixture containing sawdust, naphthalene and iron filings?

• By using Magnetic separation iron filings can be removed from saw dust and naphthalene.
• By using the Sublimation process we can separate naphthalene from saw dust.

5. How are homogenous solutions different from heterogeneous solution? Explain with examples.

6. Why are gases easily compressible whereas solids are incompressible?

The atoms and molecules in gases are much more spread out than in solids or liquids. They move freely and vibrate freely at high speed.

7. Hold a ‘Smiley ball’ and squeeze it can you compress it? Justify your answer.

A smiley ball has minute holes, in which air is trapped. When we press it the air is expelled out. So we are able to compress.

VII. Answer in Detail

1. Write the differences between elements and compounds and give an example for each.

2. Explain the Tyndall effect and Brownian movement with a suitable diagram.

Tyndall Effect

• When a strong beam of light is focused on a colloidal solution the path of the beam becomes visible. This phenomenon is known as the Tyndall effect.
• The path of light is visible due to the scattering of light by colloidal particles.
• The colloidal particles become self-luminous due to the absorption of light energy which is then scattered from their surface.
• The maximum scattered intensity in the plane is at a right angle to the path of the light and thus the path becomes visible when observed from the sides.

Brownian Movement

• It is a kinetic property.
• When colloidal solutions are viewed under a powerful microscope.
• It can be seen that colloidal particles are moving constantly and rapidly in zig-zag directions.
• The Brownian movement of particles is due to the unbalanced bombardment of the particles by the molecules of the dispersion medium.

3. How is a mixture of common salt, oil and water separated? You can use a combination of different methods.

Separation of oil from the mixture

This can be done by using a separating funnel.

• A repasting funnel is taken. The lid is opened and the given mixture is poured into it.
• The funnel is shaken well. The oil layer will float over the water layer.
• The stopcock is opened to collect salty water first.
• After this, the oil layer is collected in another beaker.

Separation of salt from water

• The salty water is taken into the distillation flask and heated for boiling.
• The pure water vapour passes through the inner tube of the condenser.
• This on cooling condenses into pure water and gets collected in a receiver.
• The salt is left behind in the flask as a residue, which can be collected separately.

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Last Updated: 1st July 2023