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NCERT Solutions for Class 9 Science Chapter 2 Is Matter Around Us Pure: Is matter around us Pure Class 9 is a part of NCERT Solutions for Class 9 Science. Through the chapter of NCERT solutions, you will be able to understand that pure substances can be elements or compounds. An element is a form of matter that can't be weakened by chemical reactions into simpler substances and a compound is a substance composed of two or more different types of elements. They are chemically combined in a fixed proportion and the properties of a compound are different from its constituent elements, whereas a mixture shows the properties of its constituting elements or compounds. The solutions for NCERT Class 9 Science Chapter 2 Is Matter Around Us Pure cover all the questions mentioned at the end of the chapter and additional questions mentioned in between the chapter. Students can also download the class 9 science chapter 2 pdf and use them according to their comfort for free.
In NCERT Class 9 Science chapter Is matter around us pure, you will get to know about types of mixtures, how to separate the components of a mixture, types of pure substances and physical and chemical changes. The NCERT class 9 science chapter 2 exercise solutions are here to help you to understand all the important topics mentioned in the NCERT syllabus through questions. If you have any problem answering the questions or you are not getting the correct answers then don't worry, CBSE NCERT solutions for Class 9 Science chapter 2 Is Matter Around Us Pure is there for you to help.
Free download class 9 science chapter 2 solutions PDF for CBSE exam.
Topic 2.1 What is a mixture?
Q 1. What is meant by a substance?
Answer:
Substance-
A substance is a matter which consists of a single type of particles and has specific properties. For example tin, sulfur, pure sugar (sucrose) etc.
Q 2. List the points of differences between homogeneous and heterogeneous mixtures.
Answer:
The differences between homogeneous and heterogeneous mixtures-
HOMOGENEOUS | HETEROGENOUS |
1. It has uniform compositions. 2. No visible boundaries of separation. 3. It consists of only one phase. examples- sugar + water = sugar solution | 1. It does not have a uniform composition 2. Visible boundaries of separation 3. They consist of more than one phase. examples- sugar +sand = sugar + sand |
NCERT free solutions for class 9 science chapter 2 Is Matter around us pure?
Topic 2.2 What is a solution?
Q 1. Differentiate between homogeneous and heterogeneous mixtures with examples.
Answer:
Homogeneous Mixture: It is a mixture in which different constituents are mixed uniformly and these constituents cannot be easily separated.
Example: Sugar solution, soda, water, soft drinks, vinegar, air, etc.
But,
Heterogeneous mixtures: It is a mixture in which different constituents are not mixed uniformly and the constituents can be easily seen and can be easily separated.
Example: Sugar and sand mixture, milk, ink, paint, wood, blood, etc.
Q 2. How are sol, solution and suspension different from each other?
Answer:
Difference between sol, solution and suspension are given below:
Sol(Colloids) | Suspension | Solution |
1. Heterogeneous mixture | 1. Heterogeneous mixture | 1.Homogeneous mixture |
2. We cannot see the size of the particle with a naked eye. | 2. Particles are visible by the human naked eye | 2. the particles are not visible to a naked eye. |
3. They can scatter the beam of light passing through them | 3. scatters the beam of light passing through them | 3. unable to scatter the beam of light. |
4. Solute particles cannot be separated by filtration and sedimentation. | 4. Solute particles can be separated by filtration | 4. solute particles cannot be separated by filtration and sedimentation. |
Answer:
Given that,
Mass of solute (sodium chloride) = 36 g =
Mss of water (as a solvent) = 100 g =
Therefore, the total mass of solution = 100 + 36 = 136 g =
According to question,
Concentration =
%
Hence the concentration of the solution at 293 K is 26.47%
CBSE NCERT solutions for class 9 science chapter 2 Is Matter around us pure?
Topic 2.3 Separating the components of a mixture
Answer:
The mixture of kerosene and petrol which are miscible with each other can be separated by the distillation method.
Take the mixture in a distillation flask and fit it with the thermometer. Heat the mixture slowly. As the boiling point of petrol is lower than that of kerosene, so, petrol vaporizes first. It condenses in the condenser and is collected from the outlet.
And thus kerosene is left in the flask.
Q 2. Name the technique to separate
(i) butter from curd,
(ii) salt from sea-water
(iii) camphor from salt.
Answer:
The following techniques are used to separates them-
(i) Centrifugation method
(ii) Evaporation and
(iii) Sublimation.
Q 3. What type of mixtures are separated by the technique of crystallization?
Answer:
The crystallization technique is used to purify solids.
In this method, pure solids can be separated in the form of its crystals from the solution. For example- salts from seawater can be separated by this method.
NCERT textbook solutions for class 9 science chapter 2 Is Matter around us pure?
Topic 2.4 Physical and Chemical changes
Q 1. Classify the following as chemical or physical changes:
• cutting of trees,
• melting of butter in a pan,
• rusting of almirah,
• boiling of water to form steam,
• passing of electric current, through water and the water breaking down into hydrogen and oxygen gases,
• dissolving common salt in water,
• making a fruit salad with raw fruits, and
• burning of paper and wood
Answer:
Physical changes-
Chemical changes-
Q 2. Try segregating the things around you as pure substances or mixtures.
Answer:
Pure substance - Water, sugar and gold
Mixtures- plastics papers, air and milk
Q 1. Which separation techniques will you apply for the separation of the following?
(a) Sodium chloride from its solution in water.
(b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride.
(c) Small pieces of metal in the engine oil of a car.
(d) Different pigments from an extract of flower petals.
(e) Butter from curd.
(f) Oil from water.
(g) Tea leaves from tea.
(h) Iron pins from sand.
(i) Wheat grains from husk.
(j) Fine mud particles suspended in water.
Answer:
The following separation techniques are used to separate-
a) Sodium chloride from its solution in water. by Evaporation, method
b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride. by Sublimation
c) Small pieces of metal in the engine oil of a car. by filtration.
d) Different pigments from an extract of flower petals. by chromatography,
e) Butter from curd. by centrifugation,
f) Oil from water. by separation funnel
g) Tea leaves from tea. by filtration,
h) Iron pins from sand. by magnetic separation,
i) Wheat grains from husk. by winnowing or sedimentation,
j) Fine mud particles suspended in water. by decantation and filtration .
Answer:
The steps for making a tea-
What mass of potassium nitrate would be needed to produce a saturated solution of potassium nitrate in 50 grams of water at 313 K?
Substance Dissolved | Temperature in K | ||||
283 | 293 | 313 | 333 | 353 | |
Potassium Nitrate | 21 | 32 | 62 | 106 | 167 |
Sodium Chloride | 36 | 36 | 36 | 37 | 37 |
Potassium Chloride | 35 | 35 | 40 | 46 | 54 |
Ammonium Chloride | 24 | 37 | 41 | 55 | 66 |
Answer:
We have,
Mass of potassium nitrate = 62g in 100 g of water
Therefore, according to question,
Mass of potassium nitrate in 50 g of water at 313K
Q 3.(b) Pragya tested the solubility of three different substances at different temperatures and collected the data as given below (results are given in the following table, as grams of a substance dissolved in 100 grams of water to form a saturated solution).
Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution to cool at room temperature. What would she observe as the solution cools? Explain.
Substance Dissolved | Temperature in K | ||||
283 | 293 | 313 | 333 | 353 | |
Potassium Nitrate | 21 | 32 | 62 | 106 | 167 |
Sodium Chloride | 36 | 36 | 36 | 37 | 37 |
Potassium Chloride | 35 | 35 | 40 | 46 | 54 |
Ammonium Chloride | 24 | 37 | 41 | 55 | 66 |
Answer:
Pragya will observe that, on cooling the saturated solution, the crystals of potassium chloride will be obtained.
Find the solubility of each salt at 293 K. Which salt has the highest solubility at this temperature?
Substance Dissolved | Temperature in K | ||||
283 | 293 | 313 | 333 | 353 | |
Potassium Nitrate | 21 | 32 | 62 | 106 | 167 |
Sodium Chloride | 36 | 36 | 36 | 37 | 37 |
Potassium Chloride | 35 | 35 | 40 | 46 | 54 |
Ammonium Chloride | 24 | 37 | 41 | 55 | 66 |
Answer:
The solubility of each salt at 293K is
What is the effect of change of temperature on the solubility of a salt?
Substance Dissolved | Temperature in K | ||||
283 | 293 | 313 | 333 | 353 | |
Potassium Nitrate | 21 | 32 | 62 | 106 | 167 |
Sodium Chloride | 36 | 36 | 36 | 37 | 37 |
Potassium Chloride | 35 | 35 | 40 | 46 | 54 |
Ammonium Chloride | 24 | 37 | 41 | 55 | 66 |
Answer:
Solubility is directly proportional to the temperature.
Therefore, on increasing temperature, the solubility of salt increases.
Q 4.(a) Explain the following giving examples.
saturated solution
Answer:
Saturated solution - In a given solvent, when no more solute can be dissolved in a solution at a given temperature is called a saturated solution.
Q 4.(b) Explain the following giving examples
pure substance
Answer:
Pure substance -
A pure substance is a matter which consists of a single type of particles and has specific properties. For examples tin, sulphur, pure sugar (sucrose) etc.
Q 4.(c) Explain the following giving examples.
colloid
Answer:
colloid -
A colloid is a solution in which the solute particle is bigger in size as compare to the true solution. It is a heterogeneous mixture. Because of the small size of colloidal particles, we cannot see them with naked eyes. For example milk and blood.
Q 4.(d) Explain the following giving examples.
(d) suspension
Answer:
Suspension-
It is a heterogeneous solution in which the solute particles do not dissolve in solvent but remain suspended throughout the bulk of the medium. Particles are visible by naked eyes. Chalk-water is an example of this type of solution.
Q 5. Classify each of the following as a homogeneous or heterogeneous mixture.
soda water, wood, air, soil, vinegar, filtered tea.
Answer :
The mixture of following are homogeneous in nature-
Soda water, vinegar, and filtered tea. as there are no separation boundaries in their solution.
Heterogeneous - Wood, air and soil. As we can easily see the separation boundaries.
Q 6. How would you confirm that a colourless liquid given to you is pure water?
Answer:
By boiling the give colourless water we can check that it is pure or not. If it is pure then the water boils at 100 at atmospheric pressure.
This is because the melting and boiling point of pure substance doesn't change.
Q 7. Which of the following materials fall in the category of a “pure substance”?
(a) Ice
(b) Milk
(c) Iron
(d) Hydrochloric acid
(e) Calcium oxide
(f) Mercury
(g) Brick
(h) Wood
(i) Air
Answer:
A pure substance is a matter which consists of a single type of particles and has specific properties-
Therefore, the following given substances are '' pure substance " -
Q 8. Identify the solutions among the following mixtures.
(a) Soil
(b) Seawater
(c) Air
(d) Coal
(e) Soda water
Answer:
A solution is a homogeneous mixture of two or more than two substances.
So, according to the definition, out of the given seawater, air and soda water are examples of solutions.
Q 9. Which of the following will show the “Tyndall effect”?
(a) Salt solution
(b) Milk
(c) Copper sulphate solution
(d) Starch solution.
Answer:
Tyndall effect is shown by the colloidal solution and suspension and it is not shown by a true solution.
Therefore, in the above-given solution only milk and starch solution will be able to scatter the light and hence show the Tyndall effect.
Q 10. Classify the following into elements, compounds, and mixtures.
(a) Sodium
(b) Soil
(c) Sugar solution
(d) Silver
(e) Calcium carbonate
(f) Tin
(g) Silicon
(h) Coal
(i) Air
(j) Soap
(k) Methane
(l) Carbon dioxide
(m) Blood
Answer:
Elements cannot be broken down into any simpler substance. and the compounds have fixed composition can be broken down into elements by chemical or electrochemical reactions. Mixtures have no fixed composition they are either homogeneous or heterogeneous.
Therefore, Sodium, Silver, Tin, and Silicon are elements.
Q 11. Which of the following are chemical changes?
(a) Growth of a plant
(b) Rusting of iron
(c) Mixing of iron filings and sand
(d) Cooking of food
(e) Digestion of food
(f) Freezing of water
(g) Burning of a candle.
Answer:
Out of given following are the examples of chemical changes-
Chapter No. | Chapter Name |
Chapter 1 | Matter in Our Surroundings |
Chapter 2 | Is Matter Around Us Pure |
Chapter 3 | Atoms and Molecules |
Chapter 4 | Structure of The Atom |
Chapter 5 | The Fundamental Unit of Life |
Chapter 6 | Tissues |
Chapter 7 | Diversity in Living Organisms |
Chapter 8 | Motion |
Chapter 9 | Force and Laws of Motion |
Chapter 10 | Gravitation |
Chapter 11 | Work and Energy |
Chapter 12 | Sound |
Chapter 13 | Why Do We Fall ill? |
Chapter 14 | Natural Resources |
Chapter 15 | Improvement in Food Resources |
Class 9 Chapter 2 science formula is a key tool for answering the numerical questions of this chapter since it provides the appropriate mathematical equations and relationships. In NCERT Solutions for Class 9 Science Chapter 2: Is Matter Around Us Pure, the following significant formulas are covered:
This formula relates the density of a substance to its mass and volume, helping us determine the compactness of a material.
This formula calculates the molarity of a solution, which represents the concentration of a solute in a given volume of the solution.
This formula helps us determine the percentage by mass of a solute in a solution, providing insights into the composition of the solution.
This formula allows us to calculate the number of water molecules associated with a hydrated salt.
These are some of the important formulas of chemistry class 9 chapter 2 which will help you to solve all the questions related to NCERT class 9 science chapter 2 exercise solutions matter around us. Students can also download the PDF of the important formula for class 9 by clicking on the given suggestion link.
Some important topics covered in the science chapter 2 "Is Matter Around Us Pure" include:
Water: Examining water's importance as a solvent and its function in purifying procedures.
Separation Techniques: Learning various techniques like filtration, evaporation, and sublimation for separating mixtures.
These topics of Science Class 9 chapter 2 provide a foundation for understanding the purity of matter and the methods used to analyze, separate, and purify substances.
Also Check-
NCERT Books and NCERT Syllabus :
Chapter No. | Chapter Name |
Chapter 1 | Chapter 1 Matter in our Surroundings |
Chapter 2 | Chapter 2 Is Matter Around Us Pure? |
Chapter 3 | Chapter 3 Atoms and Molecules |
Chapter 4 | Chapter 4 Structure of the Atom |
Chapter 5 | Chapter 5 The Fundamental Unit of Life |
Chapter 6 | Chapter 6 Tissues |
Chapter 7 | Chapter 7 Diversity in Living Organisms |
Chapter 8 | Chapter 8 Motion |
Chapter 9 | Chapter 9 Forces and Laws of Motion |
Chapter 10 | Chapter 10 Gravitation |
Chapter 11 | Chapter 11 Work and Energy |
Chapter 12 | Chapter 12 Sound |
Chapter 13 | Chapter 13 Why do We Fall ill? |
Chapter 14 | Chapter 14 Natural Resources |
Chapter 15 | Chapter 15 Improvement in Food Resources |
NCERT exemplar for Class 9 Science can be used to practice more questions. The questions in the exemplar are of different type. There are objective type questions, short answer type, fill in the blanks and long answer type questions. There are 42 practice questions given. These NCERT book questions and examplar questions are helpful for exam like NSEJS.
Matter can exist as pure substances, composed of a single element or compound, or as impure mixtures containing multiple substances.
Mixtures, which are combinations of two or more components, are referred to as impure matter. Solutions, suspensions, and colloids are examples of impure matter since they combine many ingredients without having a predetermined makeup.
A substance's physical and chemical qualities can be changed by impurities. They might alter its conductivity, reactivity, melting or boiling temperature, performance, or usefulness in a variety of applications.
Yes, a mixture can be converted into a pure substance through various separation techniques. For example, distillation can be used to separate a mixture of liquids based on their boiling points, resulting in the collection of individual pure components.
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