Is Matter Around Us Pure, Class 9th Notes

THESE NOTES ARE PREPARED ACCORDING TO JKBOSE SYLLABI IN SIMPLIFIED AND CONCISE PATTERN

Exercises

Q. What is meant by Pure substance?

Ans: The substance which is having no adulteration is pure substance.

In other words, a pure substance is one which consists of single type of particles.

Q. What is meant by a substance?

Ans: Substance is another name of Matter. It can be defined as the matter with specific composition and properties. 

Q. What is mixture? What are the types of mixture?           Or

Differentiate between Homogeneous and Heterogeneous mixture.

                                                                                           Or

List the points of differences between homogeneous and heterogeneous mixtures

Ans: Mixture is the form of matter which consists of more than one type of substance.

In a mixture, the different substances can't be seperated by Physical process.

Mixture is of two types:

1. Homogeneous mixture: Homogeneous mixture has uniform composition. They are also called Solutions.

E.g. Salt water, Sugar Solution.

2. Heterogeneous mixture: Heterogeneous mixture has non uniform composition and is physically distinct.

E.g Oil in water, Iron fillings in sand.



Q. Define Solution. What are the properties of solution?

Ans: A Solution is homogeneous mixture of two or more substances. It consists of Solute inside the Solvant.

The examples are salt water, soda water, air, alloys.

Properties:

I. Solutions are homogeneous.
II. Particle size is small in nano meters
III. They dont scatter beam of light.
IV. Particles of solution do not settle down.
V. Solution can't be seperated by Filteration.



Q. What is Suspension? What are the properties of Suspension.

Ans: Suspension is heterogeneous mixture where in solid substance is dispersed in liquid.

Properties:

I. Suspension is a Heterogeneous mixture.
II. It scatters beam of light.
III. The solute particles settle down when suspension is left undisturbed.
IV. It can be filtered.


Q. What is a Collidal solution? What are different types of Collidal solutions.

Ans: A Collidal solution is hetergenous mixture which appears to be homogeneous.
Its particle size is very small.
It scatter beam of light.
It cannot be filtered.

The collidal solution has dispersion medium and dispersed phase.

Types of Collidal Solutions:
Aerosols, Foam, Emulsion, Gel etc.

Examples of Collidal solutions:
Milk, Jelly, Alloys, Mud etc.




Q. What is centrifugation? What are its applications?

Ans: Centrifugation is a technique for the seperation of mixtures.

The principle of centrifugation is that denser particles stay at bottom and lighter particles move to top when spun rapidly.


Applications:

I. It is used to seperate cream from milk.
II. It is used in blood and urine tests.




Q. What is Sublimation? How you can seperate mixture of salt and ammonium chloride?

Ans: Sublimation is the process of direct conversion of solid into gas. E.g Ammonium chloride, Camphor, Napthelene, Iodine crystalls etc.

Ammonium chloride and Salt look similar and are impossible to seperate physically.

When both are heated in a flask, the ammonium chloride undergoes Sublimation and gets deposited at cooler walls of flask.

The salt remains at the bottom.

Q. How are Sol, solution and suspension different from each other?

Ans: 

  

Solution	Suspension	Sol
It is Homogenous	It is Heterogenous	It is Heterogenous but looks Homogenous
Particle size is very small	Particle size is large	Particle size is medium
It does not show Tyndall effect	It shows Tyndall effect	It shows Tyndall effect
It cannot be separated by Filtration	It can be separated by Filtration	It can be separated by Filtration
E.g. Salt Solution	E.g. Chalk in water	E.g. Milk, Blood

 

Q. What is Chromatography? What are its applications?

Ans: Chromatography is a technique of seperation of coloured compounds based on their solubility in a solution and size.

It is of many types e.g Paper chromatography, Thin layer chromatography, gas chromatography etc

Applications:

I. It is used to separate different colours in a dye.
II. It is used to seperate  different pegments in a natural colour.
III. It us used to seperate drugs from blood.




Q. What is Distillation? How can you seperate two miscible liquids?

Ans: Distillation is a process of seperation of mixture of miscible liquids.

The basic idea behind distillation is that two liquids having difference in boiling temperature.

E.g Acetone and Water can be seperated by Distillation.
When boiled, the acetone boils at 56 C while as water boils at 100 C. The acetone is collected in different flask.



Q. What is crystallization? What are its applications?    Or

What type of Mixtures are seperated by Crystallization?

Ans: Crystallization is process of seperation of  pure solid in form of crystals from a solution.

It is used to purify solids e.g Copper sulphate from impurities.
It is used to seperate salt from sea water.

Process:

The solid along with impurities is dissolved in water.

It is then filtered where the impurities are removed.

The filterate is then heated to get crystalls of solid.

The crystals are kept overnight in filter paper so all moisture is removed.

Q. To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293 K. Find its concentration at this temperature.

Ans:  Given,

Mass of Sodium Chloride = 36 g

Mass of Water = 100 g

Temperature = 293 K

We Know,

Concentration of Solution = Mass of Solute/Mass of Solution x 100

                                              = 36/136 x 100

                                             = 26.4 %

Q. Differentiate between Physical change and Chemical change?

Ans:

Q. Distinguish between Mixture and Compound?

Ans:

Q. How will you separate a mixture containing Kerosene and Petrol which are miscible with each other?

Ans: Kerosene and Petrol are miscible and can be separated by Distillation. Petrol has low boiling point of 95C where as Kerosene has boiling point of 200C. Both the liquids are heated in a distillation flask, the petrol vaporizes first and is collected in the condenser outlet. 

Q. Name the Technique used to separate

a. Butter from Curd   b. Salt from Sea water   c. Camphor from Salt

Ans:  

Butter from Curd	Centrifugation
Salt from Sea Water	Evaporation
Camphor from Salt	Sublimation

 

 

 Q. Classify the following as chemical or physical changes:

A.  cutting of trees,              b. melting of butter in a pan,

c.  rusting of almirah,         d. boiling of water to form steam,

e. passing of electric current, through water and the water breaking down into hydrogen and oxygen gases,

f.  dissolving common salt in water,        g.  making a fruit salad with raw fruits, and

h. burning of paper and wood.

Ans:

Cutting of Trees	Physical Change
Melting of Butter	Physical Change
Rusting of Almirah	Chemical Change
Boiling of Water	Physical Change
Passage of Electricity through Water	Chemical Change
Dissolving Salt in Water	Physical Change
Mixing fruit salad	Physical Change
Burning of Paper	Chemical Change

 

 

 Q. 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

Ans:

Sodium chloride from its solution	Evaporation
Ammonium chloride from Sodium Chloride	Sublimation
Small pieces of metal in the engine oil of a car	Filtration
Different pigments from an extract of flower petals	Chromatography
Butter from curd	Centrifugation
Oil from water	Separating Funnel
Tea leaves from tea	Filtration
Iron pins from sand	Magnetic Separation/ or Sieving
Fine mud particles suspended in water	Decantation and Filtration

 

Q. Write the steps you would use for making tea. Use the words solution, solvent, solute, dissolve, soluble, insoluble, filtrate and residue.

Ans: We will use following steps for making tea:

i. We will take some water and milk as a solvent.

ii. Then we will add some tea leaves and dissolve sugar in it as a solute.

iii. The tea leaves are insoluble where as sugar is soluble in the solute.

iv. We will heat the solution till it starts boiling.

v. We will collect the filtrate in a cup and throw away the residue.

 

Q. 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 substance dissolved in 100 grams of water to form a saturated solution).

(a) What mass of potassium nitrate would be needed to produce a saturated solution of potassium nitrate in 50 grams of water at 313 K?

Ans: To produce a saturated solution of potassium nitrate in 50 g of water, 62/100 x 50 = 31g of Potassium nitrate is needed.

 

(b) 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.

Ans: When the solution cools, some particles of Potassium chloride will collect at the bottom of the beaker due to the decrease in solubility.

(c) Find the solubility of each salt at 293 K. Which salt has the highest solubility at this temperature?

Ans: The solubility of each salt at 293 K is

(i) Potassium nitrate: 32 g.
(ii) Sodium chloride: 36 g.
(iii) Potassium chloride: 35 g.
(iv) Ammonium chloride: 37 g.
Clearly, the solubility of Ammonium chloride is highest at this temperature.

(d) What is the effect of change of temperature on the solubility of a salt?

Ans: The solubility of the salt increases with the increase in the temperature.

Q. Classify each of the following as a homogeneous or heterogeneous mixture. soda water, wood, air, soil, vinegar, filtered tea.

Ans:

Soda Water	Homogeneous
Wood	Heterogeneous
Air	Homogeneous
Soil	Heterogeneous
Vinegar	Homogeneous
Filtered Tea	Homogeneous

 

 

Q. How would you confirm that a colorless liquid given to you is pure water?

Ans: Pure water is colorless, odorless, tasteless and has melting point of 0 C and the boiling point of 100C.

We can confirm by observing any of the above property.

 

Q. 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

Ans: A pure substance is the substance which cannot be separated by physical processes such as elements and compounds. From the above list, Ice, Iron, Hydrochloric acid, Calcium oxide, Mercury are pure substances.

 

Q. Identify the solutions among the following mixtures. (a) Soil (b) Sea water (c) Air (d) Coal (e) Soda water

Ans: A solution is a type of mixture which contains solute inside a solvent.

Among the above mixtures, Sea water, Air, Soda water are solutions.

 

Q. Which of the following will show “Tyndall effect”? (a) Salt solution (b) Milk (c) Copper sulphate solution (d) Starch solution

Ans: Only Suspensions and Colloidal solutions sow the Tyndall effect, so only Milk and Starch solution will show Tyndall effect.

 

Q. 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

Ans:

Sodium	Element
Soil	Mixture
Sugar Solution	Mixture
Silver	Element
Calcium Carbonate	Compound
Tin	Element
Silicon	Element
Coal	Mixture
Air	Mixture
Soap	Mixture
Methane	Compound
Carbon Dioxide	Compound
Blood	Mixture

 

 

Q. 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

Ans:

Growth of Plant	Chemical Change
Rusting of Iron	Chemical Change
Mixture of Iron filings and Sand	Physical Change
Cooking of Food	Chemical Change
Digestion of Food	Chemical Change
Freezing of Water	Physical Change
Burning of Candle	Chemical Change

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