Samacheer Kalvi 9th Science Solutions Chapter 10 Pdf

Samacheer Kalvi 9th Science Solutions Chapter 10 Pdf

Tamilnadu Board Samacheer Kalvi 9th Science Solutions Chapter 10: Tamilnadu State Board Solution Class 9 Science Chapter 10 – MATTER AROUND US.

Samacheer Kalvi 9th Science Solutions Chapter 10: Overview

Board	Samacheer Kalvi
Class	9
Subject	Science
Chapter	10
Chapter Name	MATTER AROUND US

Samacheer Kalvi 9th Science Solutions Chapter 10 Pdf

Chapter 10
Matter around us

Exercise:

I. Choose the correct answer.

1) The separation of denser particles from lighter particles done by rotation at high speed is called _____________
a) Filtration
b) Sedimentation
c) Decantation
d) Centrifugation
Ans: d) Centrifugation
In centrifugation, due the high speed of rotation heavier solid particles moves down and the lighter liquid remains on the top.

2) Among the following ___________ is a mixture
a) Common Salt
b) Juice
c) Carbon dioxide
d) Pure Silver
Ans: b) Juice
Because, juice contains a pulp of fruit and liquid also which is a homogenous mixture.

3) When we mix a drop of ink in water we get a ________________
a) Heterogeneous Mixture
b) Compound
c) Homogeneous Mixture
d) Suspension
Ans: c) Homogeneous Mixture
Because, the ink will mix well in water and water becomes bluish coloured and which forms the homogeneous mixture.

4) ________________ is essential to perform separation by solvent extraction method.
a) Separating funnel
b) Filter paper
b) Centrifuge machine
d) Sieve
Ans: a) Separating funnel
Because, in solvent extraction method the separating funnel is used to separate two immiscible liquids.

5) __________ has the same properties throughout the sample
a) Pure substance
b) Mixture
c) Colloid
d) Suspension
Ans: a) Pure substance
Because, pure substance is made from only one kind of material due to which every part of it retains the same properties throughout.

II. State whether true or false. If false, correct the statement.

1) Oil and water are immiscible with each other.
Ans: True

Oil and water are immiscible with each other because when we add the oil in water, oil floats on water. This is because, the density of oil is less than the density of water.

2) A compound cannot be broken into simpler substances chemically.
Ans: False
A compound is made up of two or more than two kind of elements and hence when we broke it must be broken into simpler substances chemically.

3) Liquid – liquid colloids are called gel.
Ans: False
Because, the liquid-solid colloids are called as gels.

4) Buttermilk is an example of heterogeneous mixture.
Ans: True

5) Aspirin is composed of 60% Carbon, 4.5% Hydrogen and 35.5% Oxygen by mass. Aspirin is a mixture.
Ans: False
Because, all the constituents of Aspirin are in fixed proportion by mass and hence it is a compound.

III. Match the following.

Ans:
Element : Pure substance
Compound: Made up of molecules
Colloid : made up of atoms
Suspension : Settles down on standing
Mixture : impure substance

IV. Fill in the blanks.

1) A ________________ mixture has no distinguishable boundary between its components.
Ans: A homogenous mixture has no distinguishable boundary between its components.

2) An example of a substance that sublimes is ________________
Ans: An example of a substance that sublimes isIodine, Camphor.

3) Alcohol can be separated from water by _________________
Ans: Alcohol can be separated from water by Fractional distillation.

4) In petroleum refining, the method of separation used is ______________
Ans: In petroleum refining, the method of separation used is Fractional distillation.

5) Chromatography is based on the principle of ______________
Ans: Chromatography is based on the principle of distribution coefficient

V. Answer very briefly.

1) Differentiate between absorption and adsorption.
Ans: Adsorption is the process in which particles of one substance are deposited only on the surface of another substance. Absorption is the process in which the substance is uniformly distributed throughout the bulk of another substance.
For example: when we deep the chalk stick into the ink then the chalks surface appears blue due to adsorption of colored molecules on the surface of chalk. And the ink solvent get absorbed inside the chalk also. Due to which when we break that chalk stick, we see that it appears white from inside. Thus, this is the best example to explain the difference between adsorption and absorption.

2) Define Sublimation.
Ans: The process in which when the solid substances are heated they are directly converted into gases without converting into liquid state is called as sublimation. And when again if we cooled this vapor then again it is converted into solid. For example: Iodine, camphor, ammonium chloride etc. On heating directly converted into gases.

3) A few drops of ‘Dettol’ when added to water the mixture turns turbid. Why?
Ans: When we add few drops of Dettol in a water then it turns water turbid. Because, water and Dettol are immiscible in one another due to which Dettol particles get suspended in water to emulsion. An emulsion is the colloid of two or more immiscible liquids where one liquid dispersed over another liquid. Due to which one type of liquid particles get scattered in another liquid.

4) Name the apparatus that you will use to separate the components of mixtures containing two,.
Ans:  Miscible liquids:
To separate the two or more miscible liquids which have very small difference in their boiling point, the method used is called as fractional distillation. Fractional distillation is mainly used in petrochemical industry in order to obtain different fractions of petroleum and to separate the more gases from air distill alcohol.
Immiscible liquids:
The two immiscible liquids can be separated by solvent extraction method. For example: the mixture of oil and water is separated by using a particular funnel. This method is used in pharmaceutical and petroleum industries.

5) Name the components in each of the following mixtures.
Ans: 1) Ice cream: the main components in ice cream are milk powder, fat, eggs, color flavors, sugar and gelatin.
2) Lemonade: lemonade is the mixture of lemon Juice, water and sugar.
Air: air is the mixture of nitrogen, oxygen, carbon dioxide and other gases with water vapor also.
Soil: it is the mixture of sand, many salts, and clay and dust particles also.

VI. Answer briefly.

1) Which of the following are pure substances? Ice, Milk, Iron, Hydrochloric acid, Mercury, Brick and Water.
Ans: Iron, ice, mercury, water and hydrochloric acid are the pure substances. Because they are in the pure form only. And milk, brick are not the pure substances.

2) Oxygen is very essential for us to live. It forms 21% of air by volume. Is it an element or compound?
Ans: The oxygen O2 is the element which is made from two atoms of oxygen only.And has a fixed symbol and made up of atoms of the same kind. And hence oxygen is an example of an element.

3) You have just won a medal made of 22-carat gold. Have you just procured a pure substance or impure substance?
Ans:
The medal is made of 22 carat gold, it means that it’s not pure and some copper is added in it. Because the pure gold is exist in the form of 24 carat. Since the purity of gold is measured in carat.
Here, (22/24)*100 = 91.66%
Here, the 91.66% is the gold in the 22 carat of gold medal and remaining 0.34% is the copper added.

4) How will you separate a mixture containing saw dust, naphthalene and iron filings?

Ans: We will separate the mixture of saw dust, naphthalene and iron feelings firstly using magnet. When we move the magnet throughout the mixture the iron feelings will be attracted and only the mixture of saw dust and naphthalene is remained. Now to separate them, put the mixture in China dish and covered it with the perforated asbestos sheet over which inverted funnel is placed. By closing the open end of the funnel with cotton we will heat the China dish slowly. Then after sometime the naphthalene get vaporized through the asbestos sheet and then cooled on the inner side of funnel. Then only the saw dust will be remained in the China dish. In this way we can separate the mixture of saw dust, iron feelings and naphthalene easily.

5) How are homogenous solutions different from heterogeneous solution? Explain with examples.
Ans: The homogeneous mixture is the solution of uniform composition throughout and we cannot see the particles separately. The heterogeneous mixture is the solution in which there is no uniform composition throughout the solution and we can see the components separately. Every part of homogeneous solution has the same properties. For example: tap water, milk, ink salt solutions are homogeneous solutions. Every part of heterogeneous solution does not have the same properties. For example: soil is a heterogeneous mixture of iodine and salt, mixture of sand and sugar.

VII. Answer in detail.

1) Write the differences between elements and compounds and give an example for each.
Ans:
All substances on earth are made from certain simple substances called as elements. Hence, elements are the building blocks of all the materials. When two or more elements chemically combined together to form a new substance, then that new substance is called as compound. Elements are made from only one kind of atom while compounds are made from more than one kind of atoms. In elements, the smallest particle which retains the all its properties is only the atom from which element is formed. In compounds, the smallest particle which retains all its properties is the molecule. Elements cannot be broken into smallest part again. While compounds are broken down into elements by using chemical methods. For example: aluminum is the element which is made from only one atom of aluminum. Sugarcane is the compound made from carbon, hydrogen and oxygen.

2) Explain Tyndall effect and Brownian movement with suitable diagram.
Ans: Tyndall effect:  Tyndall observed that, when a strong beam of light is passed through the colloidal solution then the path of light becomes visible. This phenomenon is called as Tyndall effect. The path along which light is illuminated is called as Tyndall cone. Tyndall effect is observed only in colloidal solution only not in true solutions. The familiar examples of Tyndall effect are, the beam of light coming from headlights of the vehicles is due to the Tyndall effect. The blue color of the sky is also due to the Tyndall effect.
Brownian motion:

Fig. Brownian motion

When we see the colloidal solution under the strong microscope, it is observed that the colloidal particles are moving constantly and randomly in zigzag modes. This movement of particles is due the unbalanced bombardment of the particles by the molecule of dispersed medium.

For example: when the pollen grains are suspended on water, the motion of pollen grains is the Brownian motion. This happens because water molecules are moving faster which moves the pollen grains on the surface of water firstly and the motion we see is the Brownian motion.

3) How is a mixture of common salt, oil and water separated? You can use a combination of different methods.
Ans: The mixture of oil, common salt and water is separated as given below: We take this mixture in a beaker and allow it as it is for few minutes then the whole oil floats on water because the density of oil is less than water. And also the salt will be dissolved in the water. Now the mixture of two immiscible liquids i.e. oil and water is separated by using separating funnel. And the remaining part in the funnel only oil. In this way oil can be separated from solution of salt and water. Now, to separate this miscible solution, we heat salt water in a distillation flask with a water condenser. The pure water get evaporated in the tube of condenser and after cooling it, the pure water is collected in receiver. The residue remained after this whole process in the flask is the only salt. In this way we can separate the miscible solution by fractional distillation method and the immiscible solution by solvent extraction method.

 

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