Notes of Ch 2 Is Matter Around us Pure| Class 9th Science

Notes of Ch 2 Is Matter Around us Pure| Class 9th Science

Topics in the Chapter

• Introduction
• What is Mixture and its types
• What is a solution and its properties
• Concentration of a solution

4. The solute particles cannot be separated from the mixture by the process of filtration.

5. The solution is stable and solute particles do not settle down when left undisturbed

.

Concentration of a solution

(i) Saturated solution: When no more amount of solute can be dissolved in a solution at a given temperature, it is called a saturated solution.

(ii) Unsaturated solution: When more amount of solute can be dissolved in a solution at a given temperature, it is called a saturated solution.

(ii) Solubility: The amount of the solute present in the saturated solution at the given temperature is
called its solubility.

The concentration of a solution is the amount of solute present in a given amount (mass or volume) of solution. Also, the amount of solute dissolved in a given mass or volume of solvent is called concentration of solution.

Concentration of solution = Amount of solute/Amount of solvent or Amount of solute/Amount of solution
(Here, amount means mass or volume)

Two methods of finding concentration of solution:

(i) Mass by mass percentage of a solution = (Mass of solute/Mass of solution) ×100

(ii) Mass by volume percentage of a solution = (Mass of solute/Volume of solution) ×100

What is a suspension and its properties

A suspension is a heterogeneous mixture in which the the solute particles do not dissolve but remain suspended throughout the bulk of the medium. Ex: Chalk in water, smoke in the air

Properties of Suspension :

1. It is a heterogeneous mixture.

2. Particles of a suspension are visible to the naked eye.

3. Size of the particles is greater than 100 nm.

4. It is unstable mixture. Solute settles down at the bottom over period of time.

5. If the solution is passed through filter paper, solute and solvent gets separated.

6. It scatters light when light is passed through the solution i.e. it shows Tyndall effect.


What is a colloidal solution and its properties

Colloid solution is heterogeneous mixture in which the size of particles lies between the true solutions and suspensions.

• Colloidal particles can easily scatter a beam of visible light. This phenomenon is called Tyndall effect.

Properties of colloidal solution:

1. The particles of colloid can’t be seen by naked eyes individually.

2. It is a heterogeneous mixture and thus solute and solvent can’t be separated by filter paper.

3. Size of particles is smaller than suspensions but greater than solutions (1 nm to 100 nm).

4. It is a stable mixture. Particles do not settle down at the bottom over a period of time.

5. They do not settle down when left undisturbed which means colloid is quite stable.

Different methods of separation are used to get individual components from mixture. Heterogeneous mixtures can be separated into their respective constituents by simple physical methods like handpicking, sieving, filtration etc.

Obtaining coloured components from blue/black ink

Process of evaporation is used to obtain coloured components from blue/black ink. The process of evaporation is used to separate a substance which is dissolved in water.

• It is based on the fact that liquid vaporises easily than the solid.

• Helps in separating volatile substances from non-volatile substances.

Obtaining coloured components from blue/black ink

Process of evaporation is used to obtain coloured components from blue/black ink. The process of evaporation is used to separate a substance which is dissolved in water.

• It is based on the fact that liquid vaporises easily than the solid.

• Helps in separating volatile substances from non-volatile substances.

क्षितिज पाठ 1 दो बैलों की कथा प्रश्न उत्तर

प्रश्न अभ्यास 

1. कांजीहौस में क़ैद पशुओं की हाजिरी क्यों ली जाती होगी?

उत्तर

कांजीहौस में कैद पशुओं की हाज़िरी इसलिए ली जाती होगी ताकि कैद पशुओं की संख्या का पता चल सके और पता लगाया जा सके की उनमें से कोई भाग या मर तो नहीं गया है।

2. छोटी बच्ची को बैलों के प्रति प्रेम क्यों उमड़ आया ?

उत्तर

छोटी बच्ची की माँ मर चुकी थी। वह माँ के बिछुड़ने का दर्द जानती थी। इसलिए जब उसने हीरा-मोती की व्यथा देखी तो उसके मन में उनके प्रति प्रेम उमड़ आया। उसे लगा की वे भी उसी की तरह अभागे हैं और अपने मालिक से दूर हैं।

3. कहानी में बैलों के माध्यम से कौन-कौन से नीति-विषयक मूल्य उभरकर आए हैं ?

उत्तर 

इस कहानी के माध्यम से निम्नलिखित नीति विषयक मूल्य उभरकर सामने आए हैं :
1 विपत्ति के समय हमेशा मित्र की सहायता करनी चाहिए।
2 आजादी के लिए हमेशा सजग एवं संघर्षशील रहना चाहिए।
3 अपने समुदाय के लिए अपने हितो का त्याग करने के लिए तैयार रहना चाहिए।
4 आज़ादी बहुत बड़ा मूल्य है। इसे पाने के लिए मनुष्य को बड़े-से-बड़ा कष्ट उठाने को तैयार रहना चाहिए।

4. प्रस्तुत कहानी में प्रेमचंद ने गधे की किन स्वभावगत विशेषताओं के आधार पर उसके प्रति रूढ़ अर्थ 'मूर्ख' का प्रयोग न कर किसी नए अर्थ की ओर संकेत किया है ?

उत्तर

प्रेमचंद ने गधे की सहनशीलता, सीधेपन,  क्रोध न करने, हानि लाभ सुख दुःख  सामान रहने आदि गुणों के आधार पर उसे बेवकूफ के स्थान पर संत स्वाभाव का प्राणी करार दिया है जो बहुत अधिक सीधेपन के कारण सामान के पत्र नही समझा जाता।

5. किन घटनाओं से पता चलता है कि हीरा और मोती में गहरी दोस्ती थी?

उत्तर

• दोनों एक दूसरे को चाटकर और सूंघकर अपना प्रेम प्रकट करते थे।
• जब ये दोनों बैल हल या गाड़ी में जोत दिए जाते तो दोनों ज़्यादा से ज़्यादा बोझ स्वयं झेलकर दूसरे को कम बोझ देने की चेष्टा करते।
• नाद में खली-भूसा पड़ जाने के बाद दोनों साथ ही नाँद में मुँह डालते और साथ ही बैठते थे। एक के मुँह हटा लेने पर दूसरा भी हटा लेता था।
• जब कुछ लोगों ने खेत से पकड़कर ले जाने के लिए दोनों को घेर लिया तब हीरा निकल गया परन्तु मोती के पकड़े जाना पर वह भी बंधक बनने के लिए स्वयं ही लौट आया।
• कांजीहौस की दीवार के टूटने पर जब हीरा ने भागने से मना कर दिया तो अवसर होने के बावजूद भी मोती उसे छोड़कर नहीं भागा। 

6. "लेकिन औरत जात पर सींग चलाना मना है, यह भूल जाते हो।" - हीरा के इस कथन के माध्यम से स्त्री के प्रति प्रेमचंद के दृष्टिकोण को स्पष्ट कीजिये।

उत्तर

हीरा के इस कथन से यह ज्ञात होता है कि समाज में स्त्रियों के साथ दुर्व्यवहार किया जाता था। उन्हें शारीरिक यातनाएँ दी जाती थीं। इसलिए समाज में ये नियम बनाए जाते थे कि उन्हें पुरुष समाज शारीरिक दंड न दे। हीरा और मोती भले इंसानों के प्रतीक हैं। इसलिए उनके कथन सभ्य समाज पर लागू होते हैं। असभ्य समाज में स्त्रियों की प्रताड़ना होती रहती थी।

7. किसान जीवन वाले समाज में पशु और मनुष्य के आपसी संबंधों को कहानी में किस तरह व्यक्त किया गया है?

उत्तर

प्रेमचंद ने किसान जीवन में मनुष्य तथा पशु के भावनात्मक सम्बन्धों को हीरा और मोती दो बैलों के माध्यम से व्यक्त किया है। हीरा और मोती दोनों झूरी नामक एक किसान के बैल हैं जो अपने बैलों से अत्यंत प्रेम करता है और इसी प्रेम से वशीभूत होकर हीरा और मोती अपने मालिक झूरी को छोड़कर कहीं और नहीं रहना चाहते हैं। इससे यह स्पष्ट है कि पशु भी स्नेह का भूखा होता है। प्रेम पाने से वे भी प्रेम व्यक्त करते हैं और क्रोध तथा अपमान पाकर वे भी असंतोष व्यक्त करते हैं।

8. इतना तो हो ही गया कि नौ दस प्राणियों की जान बच गई। वे सब तो आशीर्वाद देंगे ' - मोती के इस कथन के आलोक में उसकी विशेषताएँ बताइए।

उत्तर

मोती के इस कथन से उसकी निम्नलिखित विशेषताएँ उभर कर सामने आती हैं -
• वह आशावादी है क्योंकि उसे अभी भी यह विश्वास है कि वह इस कैद से मुक्त हो सकता है।

• वह स्वार्थी नहीं है। स्वयं भागने के बजाए उसने अन्य सभी जानवरों को सबसे पहले भागने का मौका दिया। 

9.आशय स्पष्ट कीजिए -
(क ) अवश्य ही उनमें कोई ऐसी गुप्त शक्ति थी, जिससे जीवों में श्रेष्ठता का दावा करने वाला मनुष्य वंचित है।
(ख) उस एक रोटी से उनकी भूख तो क्या शांत होती; पर दोनों के ह्रदय को मानो भोजन मिल गया।

उत्तर

(क) हीरा और मोती बिना कोई वचन कहे एक-दूसरे के मन की बात समझ जाते थे। प्रायः वे एक दूसरे से स्नेह की बातें सोचते थे। यद्दपि मनुष्य स्वयं को सब प्राणियों से श्रेष्ठ मानता है किंतु उसमें भी ये शक्ति नहीं होती।

(ख) हीरा और मोती गया के घर बंधे हुए थे। गया ने उनके साथ अपमान पूर्ण व्यवहार किया था। इसलिए वे क्षुब्ध थे। परन्तु तभी एक नन्हीं लड़की ने आकर उन्हें एक रोटी ला दी। उस रोटी से उनका पेट तो नहीं भर सकता था। परन्तु उसे खाकर उनका ह्रदय ज़रूर तृप्त हो गया। उन्होंने बालिका के प्रेम का अनुभव कर लिया और प्रसन्न हो उठे।

10. गया ने हीरा-मोती को दोनों बार सूखा भूसा खाने के लिए दिया क्योंकि -
क. गया पराये बैलों पर अधिक खर्च नहीं करना चाहता था।
ख. गरीबी के कारण खली आदि खरीदना उसके बस की बात न थी।
ग. वह हीरा-मोती के व्यवहार से बहुत दुखी था।
घ. उसे खली आदि सामग्री की जानकारी नहीं थी।

उत्तर

ग. वह हीरा-मोती के व्यवहार से बहुत दुखी था।

अधिक जानकारी के लिए यहां क्लिक करें

Class 9 science question answer of chapter number 1 part 3

Class 9 science question answer of chapter number 1  part 3

Question 1:Convert the following temperature to Celsius scale

(a) 300 K (b) 573 K 

Solution: By the use of given formula, we can convert the Kelvin 

temperature to Celsius.

T K –273 = t°C

(a) 300K–273 = 27°C

(b) 573K–273 = 300°C

Question 2:What is the physical state of water at 

(a) 250°C (b) 100°C?

Solution:As the boiling point of water is 100°C so(a) at 250°C, the state of water will be steam or water vapour, i.e., gaseous state. (b) at 100°C, there will be a transition of liquid state into the gaseous state. So, at this temperature, the state is/may be liquid as well as gaseous. 

Question 3:For any substance, why does the temperature remain constant during the change of state?


Solution:During the change of state of a substance, the temperature remains constant. This can be understood with the help of an example. When a solid is heated to its melting point, the temperature first rises and becomes constant when reaches its melting point. Now, on further heating, the heat energy provided to the substance helps to break the attraction force between the solid molecules. This heat is called latent heat. That is why, the temperature does not rise.

Question 4:Suggest a method to liquefy atmospheric gases.Solution:By applying pressure and reducing the temperature, atmospheric gases can be liquefied

Question 1:Why does a desert cooler cool better on a hot dry day?

Solution:A desert cooler functions on the basis of evaporation. The rate of evaporation increases with increase in temperature and decrease in humidity. As evaporation increases when the day is hot and dry. So, the desert cooler functions to a better extent.

Question 2:How does the water kept in an earthen pot (matka) become cool during summer?

Solution: Large number of tiny pores is present on the surface of the earthen pot (matka). The water stored in the earthen pot (matka) evaporates faster through these pores due to the increased exposed surface area. As the' process of evaporation causes cooling, the stored water inside the earthen pot (matka) becomes cool.

Question 3:Why does our palm feel cold when we put some acetone or petrol or perfume on it?

Solution:Acetone, petrol, perfume etc., being volatile, evaporate very 

fast when exposed to larger surfaces. During the process they absorb 

the required latent heat of vaporization from the palm (if kept on palm). So, the process causes Cooling and the palm feels cool.


Question 4:Why are we able to sip hot tea or milk faster from a saucer rather than a cup?

Solution: A liquid has large surface area in a saucer than in a cup. Thus, it evaporates faster and cools faster in a saucer than in a cup. For this reason we able to sip hot tea or milk faster from a saucer rather than a cup.

Question 5:What type of clothes should we wear in summer?

Solution:We should wear light colored cotton clothes in summer because1. Cotton is a good absorber of water/sweat. It provides more surface area for the sweat to evaporate. 

2. Light colours absorb less heat.

So, wearing light coloured cotton clothes helps us feeling cool and comfortable.



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Class 9 science question answer of chapter number 1 part 2

Class 9 science question answer of chapter number 1 part 2

Question 1:The mass per unit volume of a substance is called density. (Density = mass/volume).Arrange the following in order of increasing density–Air, exhaust from chimneys, honey, water, chalk, cotton and iron. 

Solution:We can solve this question by keeping this concept in mind. The  correct order of density for gas, liquid and solid are: Gas < Liquid < Solid. Thus, Air, exhaust from chimneys water, honey, cotton , chalk ,iron  Gas Liquid Solid -------------------------------------------------------------------------------------------> Increasing order of Density



Question 2:(a) Tabulate the differences in the characteristics of states of matter. 

(b) Comment upon the following:

Rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.

Solution:

(a)Solid :Solids have a definite volume.Solids do not tend to flow. Solids are rigid.Generally solids have a definite shape with very few exceptions like sponge, rubber band etc.Solids are generally incompressible with very few exceptions like sponge, rubber band etc.

Liquid :Liquids also have a definite volume.Liquids tend to flow.Liquids are not rigid.Liquids do not have a definite shape. They take the shape of the container.Liquids are almost incompressible.

Gases :Gases do not have a definite volume. Their volume varies with the container in which they are stored or kept.Gases also tend to flow Gases are not rigid.Gases do not have a definite shapeGases are compressible.

(b)Rigidity:Property by which an object retains its shape and size is called as rigidity. Solids are rigid whereas liquids and gases are not. Compressibility: Compressibility is the property; due to which a substance can be compressed, means its volume can be decreased. Gases are compressible whereas solids and liquids are not.Fluidity: Flowing tendency of a substance called fluidity. Gases and liquids are fluids, solids are not.Filling a gas container: a large volume of gas can be filled in a gas container bycompressing it under very high pressure. The property of compressibility (of gases) ivey sue full in this caseShape:The property of having a definite geometry is called shape of a particular substance. Solids have a definite shape whereas gases and liquids do not have.Kinetic energy: The energy possessed by a moving object or by the moving molecules of called kinetic energy. On increasing the temperature,kinetic energy of a substance (or its molecules) also increases. Molecules of gases posses highest kinetic energy.Density : The mass per unit volume of a substance is called density.

                Mass

Density = ----------

               Volume

Question 3:Give reasons:(a) A gas fills completely the vessel in which it is kept. (b) A gas exerts pressure on the walls of the container. (c) A wooden table should be called a solid.(d) We can easily move our hand in air but to do the same through a solid block of wood we need a karate expert.

Solution:(a) Force of attraction between the molecules of gases is negligible. So, molecules of gases occupy the maximum space available to them. High kinetic energy possessed by their molecules also helps for the same. (b)The motion of particles is random and having very high speed in the gaseous state.Due to this random movement, the particles hit each other and also the walls of the container. The pressure exerted by the gas is due to this force exerted by these particles per unit area on the walls of the container.(c) There is a strong force of attraction between the molecules of wood and the intermolecular space is the least. So, a wooden table has a definite shape and volume and it should be called a solid.(d) Air molecules are very-very far from each other due to negligible force of attraction working between them. So, our hand gets sufficient. space to move in air and we also displace some air molecules by applying force. But a solid block of wood has closelypacked molecules so there is no question of the movement of hand through it, in absence of suitable force in proper direction. 

Question 4:Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why? 

Solution:Liquids have lower density than that of solids. Water is also a liquid so it should also have less density than that of solid that is ice.But the case is not so and the reason for the same is the cage-like structure of ice. i.e., presence of vacant spaces between water (H2O) molecules when they linked in ice. The number of these spaces is comparatively less in water. Being more porous than water, ice is lighter than water and floats over the surface of water.

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Class 9 science question answer of chapter number 1 

Question 1:Which of the following are matters? 
Chair, air, love, smell, hate, almonds, thought, cold, cold-drink, smell of  perfume.  Solution: Any things which have some weight and occupy space will  come under category of matter.Chair, air, smell, almonds, cold-drink and smell of perfume: Matter.

Question 2:Give reasons for the following observation The smell of hot sizzling food reaches you several meters away, but to get the smell from cold food you have to go close.
Solution: Evaporation is directly proportional to temperature, means hot food evaporates easily.Diffusion of hot food vapor with air becomes very fast and can reach to a distant place within a very short time.

Question 3:A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Solution: The phenomena of cutting the water by the diver show that matter has space between its particles. 


Question 4:What are the characteristics of the particles of matter?
Solution: Characteristics of particles of matter are given below: 
1. Particles of matter have space between them. 
2. Particles of matter are continuously moving. 
3. Particles of matter have an attraction force between them. 
4. Particles of matter are very small in size

Class 9 science question answer of chapter number 1 

Question 1:Which of the following are matters? 
Chair, air, love, smell, hate, almonds, thought, cold, cold-drink, smell of  perfume.  Solution: Any things which have some weight and occupy space will  come under category of matter.Chair, air, smell, almonds, cold-drink and smell of perfume: Matter.

Question 2:Give reasons for the following observation The smell of hot sizzling food reaches you several meters away, but to get the smell from cold food you have to go close.
Solution: Evaporation is directly proportional to temperature, means hot food evaporates easily.Diffusion of hot food vapor with air becomes very fast and can reach to a distant place within a very short time.

Question 3:A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Solution: The phenomena of cutting the water by the diver show that matter has space between its particles. 


Question 4:What are the characteristics of the particles of matter?
Solution: Characteristics of particles of matter are given below: 
1. Particles of matter have space between them. 
2. Particles of matter are continuously moving. 
3. Particles of matter have an attraction force between them. 
4. Particles of matter are very small in size. . 



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