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NCERT Class 9 Science Chapter 2 Notes Is Matter Around Us Pure- Download PDF Notes

NCERT Class 9 Science Chapter 2 Notes Is Matter Around Us Pure- Download PDF Notes

Edited By Irshad Anwar | Updated on Apr 22, 2024 01:14 PM IST

Is matter around us pure is a very important to know from the chapter of the NCERT is matter around us pure. The NCERT Class 9 Science Chapter 2 notes provide the basic and detailed knowledge needed to know is matter around us pure. The main topics covered in NCERT Class 11 Biology notes are definition, what is a mixture?, types of mixtures, what is a solution?, properties of a solution, what is a colloidal solution? what is a suspension? Difference between homogeneous and heterogeneous mixtures with examples, Separating the Components Separating the Components of a Mixture of a Mixture, Physical and Chemical Changes, What are the Types of Pure Substances?, elements and compounds. Download the CBSE Notes for Class 9 Science, Chapter 2, PDF to use offline anywhere. Students must go through each topic of the is matter around us pure in Class 9 Notes Science in the easiest and most effective way possible with the help of NCERT Notes for Class 9.

Class 9 Science chapter 2 notes also cover all the important concepts related to this chapter, which are the foundation for classes 11 and 12. Is matter around us pure NCERT Notes for Class 9 Science help you revise these major concepts given in the NCERT Book in a short period of time during CBSE exam preparation. CBSE Class 9 Science Chapter 2 notes will help you with quick revision. The chapter Is Matter Around Us Pure covers all headings of NCERT. CBSE Class 9 Science chapter 2 notes also contain important examples that have been frequently asked. Having revision notes and NCERT Solutions for Class 9 Science chapter 2 handy is beneficial to save you time. The NCERT Class 9 notes PDF can be downloaded through the link given below.

Also, students can refer to:

NCERT Class 9 Chapter 2 Class Notes

Is Matter Around Us Pure

  • When a scientist states something is pure, it signifies that all of the substance's constituent particles have the same chemical nature.
  • A single sort of particle makes up a pure material.
  • A substance, in other terms, is a single pure form of matter.
  • When we look around us, we can see that most of the substance we observe is made up of two or more pure components, such as seawater, minerals, dirt, etc. these are all mixtures.

What is a Mixture?

  • Mixtures are created by simply combining two or more pure substances (components) while maintaining each substance's chemical identity.
  • Using the proper separation technique, a mixture can be separated into pure substances.

Types of Mixtures:

  • Different sorts of mixtures exist, depending on the nature of the components that make up the mixture.
  • A homogeneous mixture or solution has a consistent or uniform composition throughout.
  • A heterogeneous mixture has physically separate parts and a non-uniform composition.

What is a Solution?

Definition of Solution: A solution is a two- or more-component homogenous mixture.

  • The major component of a solution is the solvent, whereas the lesser component is the solute.
  • The amount of solute present per unit volume or unit mass of the solution/solvent can be used to determine the concentration of a solution.

Concentration of a Solution:

Based on the concentration of the solution, there are three types of solutions: diluted, Concentrated and saturated.

  • A dilute solution is one in which the amount of solute in a given mass is fairly minimal compared to the amount of solvent.
  • A concentrated solution contains a large amount of solute.
  • A saturated solution has dissolved all of the solutes it is capable of dissolving at a given temperature.
  • In other terms, a saturated solution is one in which no more solute can be dissolved in a solution at a given temperature.
  • The solubility of a solute is the amount of the solute present in a saturated solution at this temperature.
  • An unsaturated solution is one in which the amount of solute in the solution is less than the saturation level.

A solution's concentration can be stated in a variety of ways-

Mass by the mass percentage of a solution =Mass of solute x 100/Mass of solution

Mass by the volume percentage of a solution =Mass of solute x 100/Volume of solution

Volume by the volume percentage of a solution =Volume of solute x 100/Volume of solution

What is a Suspension?

Definition: A suspension is a heterogeneous combination in which the solute particles do not dissolve but stay suspended in the medium's bulk.

Properties of a Suspension:

  • Suspension is a heterogeneous mixture. A suspension's particles can be seen with the naked eye.

  • The particles in a suspension scatter a light beam travelling across it, revealing its path.

  • When a suspension is left undisturbed, the solute particles settle down, making the suspension unstable. Filtration can be used to separate them from the rest of the mixture. The suspension breaks as the particles settle down, and light is no longer scattered.

What is a Colloidal Solution?

Definition: A colloid is a type of solution in which the size of solute particles lies between that of genuine solutions and that of suspensions.

  • A colloid is a heterogeneous combination of particles that are too tiny to be seen individually with the naked eye.

  • Colloids are large enough to scatter a light beam passing through them, revealing their path.

  • When left undisturbed, they do not settle down, implying that a colloid is quite stable.

The scattering of light by particles in a colloid or particles in a very fine suspension is known as the Tyndall effect.

Dispersed phase: The dispersed phase of a colloid is the solute-like component of dispersed particles.

Dispersion medium: The dispersion medium is the component in which the dispersed phase is suspended.

Aerosol: Aerosol is a colloidal solution containing a solid/liquid dispersed phase and a dispersing medium gas, such as clouds.

Foam: Foam, for example, is a colloidal solution with a dispersed phase gas and a dispersing medium solid/liquid.

Sol: Sol is a colloidal solution including a solid dispersed phase and a liquid dispersing medium. Magnesia milk and mud

Separating the Components of a Mixture

  • To separate distinct components from a mixture, many separation procedures are used.
  • Separation enables the study and use of distinct components of a mixture.
  • Simple physical procedures like handpicking, sieving, and filtering that we employ in our daily lives can be used to separate heterogeneous mixtures into their constituents.
  • Separating the components of a mixture often necessitates the employment of specialised procedures.

Separation of Two Immiscible Liquids:

  • A separating funnel is used to separate a mixture of two immiscible liquids.
  • Application: When extracting iron from its ore, a mixture of oil and water must be separated.

Centrifugation:

  • The separation of two liquids in a mixture is accomplished by centrifugation.
  • The mixture's denser component migrates away from the axis, while the lighter component moves toward it.
  • Application: Cream is separated from milk using this method.
  • This approach can be used to separate clay particles suspended in water.

Sublimation:

  • Sublimation is the process by which a solid transforms into a gas without becoming liquid when heated.
  • This method is used to extract components from a mixture that become sublime when heated.
  • Application: Sublimation can be used to separate a mixture of common salt (sodium chloride) and ammonium chloride.

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Chromatography:

  • Chromatography is a method for separating two or more dissolved materials in extremely tiny amounts.
  • The separation is based on the notion that two or more compounds might be soluble in the same solvent yet have different solubilities.
  • Application: Black ink is made up of several different coloured substances or dyes that can be separated using paper chromatography.

Distillation:

  • Distillation is a process that uses selective evaporation and condensation to separate constituent chemicals from a liquid mixture.
  • Applications: Gasoline, distilled water, xylene, alcohol, paraffin, kerosene, and other products are all made from it.

Fractional Distillation:

  • The separation of a mixture into its constituent components or fractions based on their melting points is known as fractional distillation.
  • The boiling point is used to separate chemical substances.
  • The mixture is heated to the point where one or more of the fractions evaporate.
  • Applications: In the laboratory, fractional distillation is used to separate a mixture of miscible liquids such as acetone and water.
  • It's used to separate air gases.
  • It is used to separate crude oil, often known as "petroleum," into useful components including kerosene, gasoline, and diesel.

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  • We must separate all of the other gases present in the air if we desire oxygen gas.
  • To obtain liquid air, the air is compressed by increasing the pressure and then chilled by lowering the temperature.
  • In a fractional distillation column, where gases are separated at different heights depending on their boiling points, this liquid air is allowed to warm up slowly.

Crystallisation:

  • The cooling of a hot, concentrated chemical solution to produce crystals is known as crystallisation.
  • The crystallisation process is used to transform an impure sample into a pure solid product.
  • Applications: To obtain pure copper sulphate, impure copper sulphate can be refined using the crystallisation process.

Evaporation:

  • Evaporation is a method of separating a solid object from water or any other liquid.
  • This method is based on the fact that liquids are easily vaporised.
  • When all of the water or liquid has evaporated, the dissolved substance is left as a residue.
  • Applications: Evaporation can be used to separate common salt that has dissolved in water. Evaporation can be used to separate the coloured component of ink.

What are the Types of Pure Substances?

On the basis of their chemical composition, substances can be classified either as elements or compounds.

Elements

Elements are the most fundamental form of matter and cannot be broken down into smaller compounds by chemical reactions.

Metals, non-metals, and metalloids are the three types of elements.

Metals frequently exhibit one or more of the following characteristics:

  • They have a lustrous shine to them.

  • Their colour is silvery-grey or golden-yellow.

  • They are heat and electricity conductors.

  • They're ductile (they can be drawn into shapes).

  • Metals are malleable (they can be hammered into thin sheets).

  • They have a resonant tone to them (make a ringing sound when hit).

Gold, silver, copper, iron, sodium, potassium, and other metals are examples. Mercury is the only metal that is liquid at ambient temperature.

Non-metals typically exhibit one or more of the following characteristics:

  • They come in a wide range of colours.

  • They are poor heat and electrical conductors.

  • They lack lustre, sonority, and malleability.

Hydrogen, oxygen, iodine, carbon (coal, coke), bromine, chlorine, and other non-metals are examples.

Metalloids are elements that have properties that are halfway between those of metals and non-metals; examples include boron, silicon, and germanium.

Compounds

A compound is an entity that is made up of two or more components that have been chemically combined in a certain ratio.

Chapter-Wise NCERT Class 9 Notes Science

Significance of NCERT Class 9 Science Chapter 2 Notes:

Is matter around us pure Class 9th notes Science Chapter 2 will assist you in revising the chapter and gaining an understanding of the main concepts addressed. These Notes for Class 9 Science Chapter 2 are also not complicated, and they thoroughly explain step-by-step approaches to guarantee that students understand the concepts of this chapter, which is part of the CBSE Science syllabus for class 9. Is matter around us pure? class 9 notes pdf download can be utilised for offline preparation.

Subject Wise NCERT Exemplar Solutions

Subject Wise NCERT Solutions

Frequently Asked Questions (FAQs)

1. What are the main topics covered in the notes for class 9 Science chapter 2?

The main topics covered in Chapter 2 of NCERT Solutions for Class 9 Science are

  • Matter and its Types

  • Elements 

  • Compounds

  • Metals 

  • Nonmetals and Metalloids

  • Mixture and its Types

  • Solution and its Types 

  • Solubility and Concentration of Solution.

2. How will CBSE class 9 Science chapter 2 notes benefit students?

Subject experts have created Class 9th Science chapter 2 notes that will give you further information on the subject. You can reinforce your foundation with these class 9 science chapter 2 notes. Important concepts are well-explained here. Is Matter Around Us Pure? is explored in depth in these notes.

3. When is a solution said to be Dilute, Concentrated and saturated?
  • A dilute solution is one in which the amount of solute in a given mass is fairly minimal compared to the amount of solvent.
  • A concentrated solution is one that contains a large amount of solute.
  • A saturated solution is one that has dissolved all of the solute it is capable of dissolving at a given temperature. In other terms, a saturated solution is one in which no more solute can be dissolved in a solution at a given temperature.
4. According to Class 9th Science chapter 2 notes, Define Suspension and state its properties.

 A suspension is a heterogeneous combination in which the solute particles do not dissolve but stay suspended in the medium's bulk.

Properties of a Suspension:

As per class 9 Is Matter around us pure? Notes, properties of a suspension are given as:

  • Suspension is a mixture that is heterogeneous. A suspension's particles can be seen with the naked eye.

  • The particles in a suspension scatter a light beam traveling across it, revealing its path.

  • When a suspension is left undisturbed, the solute particles settle down, making the suspension unstable. Filtration can be used to separate them from the rest of the mixture. The suspension breaks as the particles settle down, and light is no longer scattered.

5. Distinguish between homogeneous and heterogeneous mixtures with examples.

According to Class 9th Science chapter 2 notes

Heterogeneous mixtures

Homogeneous mixtures

It shows visible boundaries of Separation.

No visible boundaries of Separation

It doesn’t have a uniform composition.

It has a uniform composition.

It consists of more than one phase.

It consists of only one phase.

6. Distinguish between Mixtures and Compounds.

According to Class 9th Science chapter 2 notes,

Compounds

Mixtures

The composition of a new substance is always fixed.

The composition of a mixture varies.

Elements react to form new compounds.

Elements or compounds just mix

to form a mixture and no new compound is formed.

The new substance has entirely new properties.

The properties of the constituent substances are displayed in a mixture.

Only chemical or electrochemical reactions can separate the constituents.

Physical methods can be used to separate the constituents fairly easily.

7. To make a saturated solution, 56g of sodium chloride is dissolved in 100 g of water at 293 K. Find its concentration at this temperature.

According to Class 9th Science chapter 2 notes, we solve the numerical as follows,

 Mass of solute (NaCl) = 56 g

Mass of solvent (H2O) = 100 g

Mass of solution (NaCl + H2O) = 156 g

Concentration = Mass of solute/Mass of solution x 100

Concentration = 56/156 x 100 = 35.89%

Hence, the concentration of the solution is 35.89%

These topics can also be downloaded from Is Matter around us pure?  class 9 notes pdf download or Class 9 Science chapter 2 notes pdf download.

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A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1)

0.34\; J

Option 2)

0.16\; J

Option 3)

1.00\; J

Option 4)

0.67\; J

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

Option 2)

 6.45×10−3 kg

Option 3)

 9.89×10−3 kg

Option 4)

12.89×10−3 kg

 

An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1)

2,000 \; J - 5,000\; J

Option 2)

200 \, \, J - 500 \, \, J

Option 3)

2\times 10^{5}J-3\times 10^{5}J

Option 4)

20,000 \, \, J - 50,000 \, \, J

A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)

K/2\,

Option 2)

\; K\;

Option 3)

zero\;

Option 4)

K/4

In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced

Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

Option 4)

67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .

How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} will contain 0.25 mole of oxygen atoms?

Option 1)

0.02

Option 2)

3.125 × 10-2

Option 3)

1.25 × 10-2

Option 4)

2.5 × 10-2

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

Option 2)

increase two fold

Option 3)

remain unchanged

Option 4)

be a function of the molecular mass of the substance.

With increase of temperature, which of these changes?

Option 1)

Molality

Option 2)

Weight fraction of solute

Option 3)

Fraction of solute present in water

Option 4)

Mole fraction.

Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

Option 2)

6.023 × 1022

Option 3)

half that in 8 g He

Option 4)

558.5 × 6.023 × 1023

A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

Option 2)

more than 3 but less than 6

Option 3)

more than 6 but less than 9

Option 4)

more than 9

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