1. Matter in Our Surroundings Science class 9 exercise Additional -Questions 2
1. Matter in Our Surroundings Science class 9 exercise Additional -Questions 2 ncert book solution in english-medium
NCERT Books Subjects for class 9th Hindi Medium
Chapter Review
Chapter Review:
- Everything in this universe is made up of material which scientists have named “matter”.
- The air we breathe, the food we eat, stones, clouds, stars, plants and animals, even a small drop of water or a particle of sand– each thing is matter.
- Matters occupy space, that is volume and have mass.
- Early Indian philosophers classified matter in the form of five basic elements – the “Panch Tatva”– air, earth, fire, sky and water.
- Modern day scientists have evolved two types of classification of matter based on their physical properties and chemical nature.
- Matter is made up of particles.
- Particles of matters have space between them.
- Particles of matters are continuously moving.
- When the temperature rises, particles move faster.
- Increasing in temperature the kinetic energy of the particles also increases.
- Particles of matter intermix on their own with each other. They do so by getting into the spaces between the particles.
- Intermixing of particles of two different types of matter on their own is called diffusion.
- Particles of matter attract each others.
- Particles of matter have force acting between them.
- There are three states of matter, i.e solid, liquid and gas.
- States of matter arise due to the variation in the characteristics of the particles of matter.
- Solids have a definite shape, distinct boundaries and fixed volumes, that is, have negligible compressibility.
- Solids have a tendency to maintain their shape when subjected to outside force.
- Solids may break under force but it is difficult to change their shape, so they are rigid.
- Liquids have no fixed shape but have a fixed volume.
- Liquids take up the shape of the container in which they are kept.
- Liquids flow and change shape, so they are not rigid but can be called fluid.
- Solids and liquids can diffuse into liquids.
- The gases from the atmosphere diffuse and dissolve in water.
- Gases, especially oxygen and carbon dioxide, are essential for the survival of aquatic animals
and plants. - All living creatures need to breathe for survival.
- The aquatic animals can breathe under water due to the presence of dissolved oxygen in water.
- Solids, liquids and gases can diffuse into liquids.
- The rate of diffusion of liquids is higher than that of solids.
- In the liquid state, particles move freely and have greater space between each other as compared to particles in the solid state.
- Gases are highly compressible as compared to solids and liquids.
- Large volumes of a gas can be compressed into a small cylinder and transported easily, due ti its high compressibility.
- Due to high speed of particles and large space between them, gases show the property of diffusing very fast into other gases.
- On increasing the temperature of solids, the kinetic energy of the particles increases.
- Due to the increase in kinetic energy, the particles start vibrating with greater speed.
- The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.
- The melting point of a solid is an indication of the strength of the force of attraction between its particles.
- The melting point of ice is 273.16 K.
- The process of melting, that is, change of solid state into liquid state is also known as fusion.
- The forces of attraction between the particles are maximum in solids, intermediate in liquids and minimum in gases.
- The states of matter are inter-convertible. The state of matter can be changed by changing temperature or pressure.
- Sublimation is the change of gaseous state directly to solid state without going through liquid state, and vice versa.
- Boiling is a bulk phenomenon. Particles from the bulk (whole) of the liquid change into vapour state.
- The rate of evaporation depends upon the surface area exposed to the atmosphere, the temperature, the humidity and the wind speed.
- Evaporation causes cooling.
- Latent heat of vaporisation is the heat energy required to change 1 kg of a liquid to gas at atmospheric pressure at its boiling point.
- Latent heat of fusion is the amount of heat energy required to change 1 kg of solid into liquid at its melting point.
- Solid carbon dioxide is also known as dry ice.
- Phenomenon of changing of a liquid into vapours at any temperature below its boiling point is called evaporation.
- Humidity is the amount of water vapour present in air.
- The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point.
Questions-Answers
Questions: NCERT Text Book/Chapter -1 /Page No.- 3
Q1. Which of the following are matter?
Chair, air, love, smell, hate, almonds, thought, cold, cold drink, smell of perfume.
Ans : Chair, air, almonds, cold drink are matter.
Q2. Give reasons for the following observation:
The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close.
Ans : It is the property of matter that increasing the temperature, the particles of matter spread very faster. Thus the smell of hot food spread faster than cool food.
Q3. A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Ans : This observation shows that the particles of matter have space between them.
Q4. What are the characteristics of the particles of matter?
Ans: The characteristics of the particles of matter are the following.
- Particles of matter have space between them.
- Particles of matter are continuously moving.
- Particles of matter attract each other.
Questions: NCERT Text Book/Chapter -1 /Page No.- 6
Q1. 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.
Ans : air, exhaust from chimneys, cotton, water, honey, chalk, iron
Q2.
(a) Tabulate the differences in the characterisitcs of states of matter.
Ans :
Solid:
- Solid have a definite shape.
- Solid have a fixed volume.
- It cannot be changed its shape.
- Inter molecular force are strongest in solid.
Liquid;
- Liquids have no fixed shape.
- Liquids flow and change shape so they are not rigid.
- They are not compressed.
- Inter molecular force are less strong in liquids.
Gas:
- Gases neither have a definite.
- They can do compressed.
- Gas can also flow.
- Inter molecular force are large space than solid and liquid.
(b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.
Ans :
- Rigidity - Rigidity is the property of solid. It means unbending (hardness). It cannot be changed its shape.
- Compressibility – The particles of matter have space between them. So the gases have more compressibility.
- Fluidity – it is a property of matter. In which matters spread on the surface.
- Filling a gas container – The state of matter which has a space between particles and property of compressibility that fills a gas container completely.
- Shape – Shape is a physical view of matter in which they acquire their size.
- Kinetic energy and density – having kinetic energy the states of matter in increasing order such as solid, liquid and gas has more kinetic energy. But in density solid is most than other and gas is lowest than all.
Q3. Give reasons;
(a) A gas fills completely the vessel in which it is kept.
Ans : Due to its high compressibility, a gas fills completely the vessels in which it is kept.
(b) A gas exerts pressure on the walls of the container.
Ans : gases show the property of diffusing very fast into other gases. In the gaseous state, the particles move about randomly at high speed. Due to this random movement, the particles hit each other and also the walls of the container.
(c) A wooden table should be called a solid.
Ans : A wooden table has the properties of a definite shape, fixed volume and intermolecular space is strong, so it 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.
Ans : The intermolecular space between the particles of air is more and therefore intermolecular force is too weak so we can easily move our hands in air. Whereas intermolecular space in solid is very strong so we need a karate expert.
Q4. Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why.
Ans: The particles of ice far away from each other while water is stronger due to hydrogen bonding. So the volume of ice is more and density is less. This make ice to float on water.
Questions: NCERT Text Book/Chapter -1 /Page No.- 9
Q1. Convert the following temperature to celsius scale:
- 300 K
- 573 K.
Ans : { changing in Celsius scale 273 is subtracted form given Kelvin value}
- 273 k = 0oC
300 k – 273 = 27o C
Hence 300k = 27o C
- 573 k – 273 = 300o C
Hence 573k = 300o C
Q2. What is the physical state of water at:
- 25 ºC
- 0ºC
- 100ºC
Ans :
- Water is liquid at 25oC.
- Water is solid at 0oC.
- Water is gas at 100oC.
Q3. For any substance, why does the temperature remain constant during the change of state?
Ans : because the heat supply is used up in changing the state by overcoming the force of attraction between the particles.
Q4. Suggest a method to liquefy atmospheric gases.
Ans : To liquefy atmospheric gases we apply pressure and reduce temperature.
Questions: NCERT Text Book/Chapter -1 /Page No.- 10
Q1. Why does a desert cooler cool better on a hot dry day?
Ans : On a hot day temperature is higher. This temperature increases the rate of evaporation cause better cooling by desert cooler.
Q2. How does the water kept in an earthen pot (matka) become cool during summer?
Ans : an earthen pot (matka) has many fine pores in it through which evaporation takes place and it absorbs heat from outside of Matka this causes increasing rate of evaporation resulting in cooling water.
Q3. Why does our palm feel cold when we put some acetone or petrol or perfume on it?
Ans : When we put some acetone or petrol or perfume on our palm it spread over palm in a large area. We know evaporation increases due to increasing surface area. It gains energy and gets evaporated cause cooling.
Q4. Why are we able to sip hot tea or milk faster from a saucer rather than a cup?
Ans : The surface area of saucer is more than the surface area of cup. The rate of evaporation is faster in saucer and therefore, cooling is also faster than cup.
Q5. What type of clothes should we wear in summer?
Ans : we should cotton clothes during summer season.
Exercise: NCERT Text Book/Chapter -1 /Page No.- 12
Q1. Convert the following temperatures to the Celsius scale.
(a) 300 K
(b) 573 K.
Ans : { changing into Celsius scale 273 is subtracted form given Kelvin value}
273 k = 0oC
300 k – 273 = 27o C
Hence 300k = 27o C
573 k – 273 = 300o C
Hence 573k = 300o C
Q2. Convert the following temperatures to the Kelvin scale.
(a) 25°C
(b) 373°C.
Ans: { changing into keivin scale 273 is added to given Celsius value}
273 k = 0oC
(a) 25°C = 25 + 273 K
= 298 k
(b) 373°C. = 373 + 273 K
= 646 K
Q3. Give reason for the following observations.
(a) Naphthalene balls disappear with time without leaving any solid.
Ans : Naphthalene is a sublimely agent which get sublimed and change directly from solid to gas. Hence Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several metres away.
Ans : It is due to diffusion. The particles of perfume move at random motion in all directions and mix with air molecules so We can get the smell of perfume sitting several metres away.
Q4. Arrange the following substances in increasing order of forces of attraction between the particles— water, sugar, oxygen.
Ans : sugar, water, oxygen.
Q5. What is the physical state of water at—
(a) 25°C
(b) 0°C
(c) 100°C
Ans :
- Water is liquid at 25oC.
- Water is solid at 0oC.
- Water is gas at 100oC.
Q6. Give two reasons to justify—
(a) water at room temperature is a liquid.
Ans : The room temperature is less than the boiling point of water and more than the temperature at this solidifies. Therefore water is liquid at room temperature.
(b) an iron almirah is a solid at room temperature.
Ans : The room temperature is not more than the its melting point. While melting point of iron is much higher. So an iron almirah is a solid at room temperature.
Q7. Why is ice at 273 K more effective in cooling than water at the same temperature?
Ans : water at 273 k takes heat during increasing in temperature but do not change it state but ice at same temperature takes heat and changes its state due to this ice is more effective in cooling than water at the same temperature
Q8. What produces more severe burns, boiling water or steam?
Ans : Steam , it boils at 373 K and has more quantity of heat due to its gaseous form it has more compression than the liquid form of water.
Additional -Questions
Que. – What are the characteristics of the particles of matter ?
Ans. - The characteristics of the particles of matter are the following.
- Particles of matter have space between them.
- Particles of matter are continuously moving.
- Particles of matter attract each other.
Que. – Write three physical state of matter.
Ans. - (i) solid
(ii) liquid
(ii) Gas
Que. – What is Evaporation?
Ans. – The phenomenon of change of a liquid into vapours at any temperature below its boiling point is called evaporation.
Que. – Give the reason for the smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close.
Ans. – It is the property of matter that increasing the temperature, the particles of matter spread very faster. Thus the smell of hot food spread faster than cool food.
Que. – A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Ans. – This observation shows that there is space between water molecules (particles of matter).
Que. – What is Fusion?
Ans – The process by which a solid get converted into liquid is known as fusion.
Que. – What is Solidification?
Ane. – The process by which a liquid get converted into solid is known as solidification.
Que. – What is sublimation?
Ane. – The process by which a solid get converted into gas directly without being converted into its liquid form is known as sublimation.
Que. – What is deffusion?
Ans. – Intermixing of particles of two different types of matter on their own is called diffusion.
Que – Write one factor which influence diffusion.
Ans – Heat.
Que. – Why is the rate of diffusion of liquids is higher than that of the solids?
Ans. – This is due to the fact that in the liquid state, particles move freely and have greater space between each other as compared to particles in the solid state.
Que – Write the factors which influence the rate of evaporation.
Ans – There are four factors which influence the rate of evaporation.
- An increase of surface area.
- An increase of temperature
- A decrease in humidity.
- An increase in wind speed
Que – Write the property of solid liquid and gas .
Ans –
Solid:
- Solid have a definite shape.
- Solid have a fixed volume.
- It cannot be changed its shape.
- Inter molecular force are strongest in solid.
Liquid;
- Liquids have no fixed shape.
- Liquids flow and change shape so they are not rigid.
- They are not compressed.
- Inter molecular force are less strong in liquids.
Gas:
- Gases neither have a definite.
- They can do compressed.
- Gas can also flow.
- Inter molecular force are large space than solid and liquid.
Additional -Questions 2
Questions-Answers (page 6) NCERT BOOK
Q1. 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.
Q2. (a) Tabulate the differences in the characterisitcs of states of matter.
(b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.
Q3. 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.
Q4. Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why?
Questions-Answers (page 9) NCERT BOOK
Q1. Convert the following temperature to celsius scale:
a. 300 K b. 573 K.
Q2. What is the physical state of water at:
a. 250ºC b. 100ºC
Q3. For any substance, why does the temperature remain constant during the change of state?
Q4. Suggest a method to liquefy atmospheric gases.
Questions-Answers (page 10) NCERT BOOK
Q1. Why does a desert cooler cool better on a hot dry day?
Q2. How does the water kept in an earthen pot (matka) become cool during summer?
Q3. Why does our palm feel cold when we put some acetone or petrol or perfume on it?
Q4. Why are we able to sip hot tea or milk faster from a saucer rather than a cup?
Q5. What type of clothes should we wear in summer?
Exercise:
Q1. Convert the following temperatures to the Celsius scale.
(a) 300 K (b) 573 K.
Q2. Convert the following temperatures to the Kelvin scale.
(a) 25°C (b) 373°C.
Q3. Give reason for the following observations.
(a) Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several metres away.
Q4. Arrange the following substances in increasing order of forces of attraction between the particles— water, sugar, oxygen.
Q5. What is the physical state of water at—
(a) 25°C (b) 0°C (c) 100°C ?
Q6. Give two reasons to justify—
(a) water at room temperature is a liquid.
(b) an iron almirah is a solid at room temperature.
Q7. Why is ice at 273 K more effective in cooling than water at the same temperature?
Q8. What produces more severe burns, boiling water or steam?
Q9. Name A,B,C,D,E and F in the following diagram showing change in its state
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Science Chapter List
1. Matter in Our Surroundings
2. Is Matter around us Pure
3. Atoms and Molecules
4. Structure of The Atom
5. The Fundamental Unit of Life
6. Tissues
7. Diversity in Living Organisms
8. Motion
9. Force and Laws of Motion
10. Gravitation
11. Work and Energy
12. Sound
13. Why Do We Fall ill
14. Natural Resources
15. Improvement in Food Resources
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