NCERT Solutions Class 9 Science Chapter 1 Matter in Our Surroundings
NCERT Solutions Class 9 Science Chapter 1 Matter in Our Surroundings: National Council of Educational Research and Training Class 9 Science Chapter 1 Solutions – Matter in Our Surroundings. NCERT Solutions Class 9 Science Chapter 1 PDF Download.
NCERT Solutions Class 9 Science Chapter 1: Overview
Board |
NCERT |
Class |
9 |
Subject |
Science |
Chapter |
1 |
Chapter Name |
Matter in Our Surroundings |
Topic |
Exercise Solutions |
NCERT Solutions Class 9 Science Chapter 1 – Matter in Our Surroundings
Intext Question and Answers
1) Which of the following are matter ?
Chair, Love , Smell, Hate, Almonds, Thought ,Cold, Lemon Water, Smell Of Perfume.
Ans– Matter is anything that has space between them,is made of particles and these particles attract each other, does among the following chair, almonds, lemon water are considered as matter.Whereas love, hate, thoughts, cold& smell of perfume is not considered as matter because they do not satisfied requirement of anything to be matter. Love, hate, thoughts are feelings. feelings are not considered as matter. smell and cold are also not considered as matter.
2) Give reason for the following,
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-This is because the particles of hot sizzling food are far from each other and they travel faster as compared to cold food. cold food particles do not travel faster in all the directions therefore the smell of hot food reaches to us faster but to smell cold food we have to go closer. As temperature increases the rate of movement of particles increases.
3) A diver is able to cut through water in swimming pool. Which property of matter does this observation show?
Ans- The property of particles of matter have force of attraction between them is observed in diver diving in swimming pool secrets of the weak force of attraction between the particles of water to swim.
4) What are the characteristics of particles of matter?
Ans-The characteristics of particles of matter are –
1) Particles of matter of space between them.
2) Particles of matter attract each other.
3) Matter is made up of particles.
5) Mass of per unit volume of a substance is called density.(density=mass/volume). Arrange the following in order of increasing density.
Air Exhaust from chimney, honey ,water ,chalk ,cotton, iron.
Ans- iron> chalk> cotton> honey> water >air exhaust in chimney.
6)
a) Tabulate the difference in characteristics of state of matter.
Ans-
Solid | Liquid | Gas |
1) Solid has big shape and volume.
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1) Liquid has fixed volume but not fixed shape.
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1) Gases do not have fixed shape or volume.
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2) Solids are rigid.
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2) Liquids are not rigid
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2) Gases are not rigid.
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3) Solids cannot be compressed.
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3) Liquids have low compressibility as compared to gases.
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3) Gases are highly compressible.
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4) The force of attraction between the particles of solid is very strong.
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4) The force of attraction between the particles and liquid is moderate.
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4) The force of attraction between gases is very less or almost negligible.
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b) Comment Upon the following Properties of Matter .
(a) Rigidity (b) Compressibility (c) Fluidity (d) Shape (e) Kinetic Energy (f) Density
Ans-
(a) Rigidity–Rigidity is the property of solid substances, which means they are in fixed shape ,they can break when force is applied but they did not change their shapes, the toughness or stiffness of a substance is considered as rigidity of a substance.
(b) Compressibility– Compressibility the change in volume of gaseous state halted to feel It in closed tight containers is compressibility.the process of a plain high pressure two gases for bringing their particles closes compressibility.
C) Fluidity– Substance that can flow of fluids and animal is called as fluidity. Requests can flow easily as they are fluids.Filling a gas container-gas container is filled easily by gases to glucose but reaction between the particles gas flow in all directions in corners of the container and feels it completely which cannot fill the container.
(d) Shape– Depends on the force of attraction between the particles present in matter. Solid surface shape due to precipitate particles. Liquid do not have fixed shape due to moderate force of attraction in particles present in them did it take the shape of container. Do not have any definite shape.
(e) Kinetic Energy-Kinetic energy is energy required for the particles to move. Kinetic energy of particles in solids is very less almost negligible they only vibrate in their fixed position. Liquid particles have more kinetic energy then solids. They are away from each other and can move faster gases have highest kinetic energy.
(f) Density – is defined the mass of substance per unit volume. Very dance liquids are less dense layer and gases are not dance at all.
7) Give Scientific Reasons.
a) A gas fills completely the vessel in which it is kept.
Ans– because gases have their particles very loosely packed and far from each other. These particles moving all the directions of container. it fills the vessel completely as the particles of gas occupy every part of the vessel.
b) A gas exerts pressure on the wall of container.
Ans- The particles of gas are in random motion. They collide on the walls of container and each other due to high pressure on particles inside the container. Therefore, gas particles exerts pressure on the walls of container.
c) A wooden table should be called solid.
Ans- a wooden table is rigid cannot change its shape and volume when external pressure is applied to it. It has a fixed shape and particles present in wooden table are closely packed. The wooden table is considered as solid.
d) We can easily move our hand in air but to do the same through a solid block of wood we need karate skills.
Ans- Particles in air are very loosely packed. They have space between them. Where as wooden block is hard particles in wooden block are very close to each other. So we can freely move our hand in air but for doing the same to wooden block karate skills are required.
8) Liquids generally have lower density as compared to solids, but you must have observed that ice floats on water. find out why?
Ans- Ice has large number of empty spaces between it’s particles as compared to water. it forms a solid shape due to freezing but its density is low as compared to water. Lower the density lighter is the substance. Therefore ice floats on water.
9) Convert the following temperature to Celsius scale.
(a) 300k (b) 573k
Ans-
a) 300k
300-273.15
26.85°c
b) 573k
573-273.15
299.85k
10)What is the physical state of water at
(a) 250°C (b) 100°C
Ans-
(a) 250°C – At 250°C water is present in gaseous state. water starts to boil at hundred degree Celsius.
(b) 100°C- At 100°C water is present in liquid state.
11) For any substance why does the temperature remains constant during the change of state?
Ans- The temperature remains constant during change in state because the heat energy supplied to the substance is used to break the force of attraction between the substance. Thus when heat is supplied, solid changes into liquid without change in temperature because the heat energy provided to solid is observed to change it into liquid state.
12) Suggest a method to liquefy atmospheric gases.
Ans- Method used to liquefy atmospheric gases applying pressure and reducing temperature.
13) Why does a dessert voter cool better on a hot dry day?
Ans- During a hot dry day the moisture present in atmosphere is very less therefore the water inside the dessert evaporates faster to cool the surrounding area.Therefore dessert water cools better on a hot dry day.
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14) Why does water kept in earthen pots become cool during summer?
Ans-Earthen pots have pores in them, water seeps out continuously through it along with heat and energy. It helps water to cool inside the pot. Thus, evaporation helps the water inside the pot to cool quickly.
15) Why does our Palm feel cold when we apply acetone or petrol or perfume on it?
Ans- When we apply acetone or petrol or perfume on it evaporates. the particles of acetone or petrol or perfume absorbs energy from Palm which is heat and evaporates along with the energy by making the surface cool therefore our palm feels cold.
16) Why are we able to SIP hot tea or milk faster from a saucer rather than a cup?
Ans-More is the surface more is the rate of evaporation.the surface area of saucer is more hence the rate of evaporation is faster and tea or milk cools faster than in cup having smaller surface area. Thus we can easily seep milk or tea fromsaucer than through cup.
17) What type of clothes should we wear during summer?
Ans-We should wear cotton clothes during summer. Cotton is a good absorber of water. Thus it helps to cool the body by absorbing sweat produced due to heat.
Exercise Question and Answer Solution:
1) Convert the following temperature to Celsius scale.
(a) 293k (b) 470k
Ans-
(a) 293k
293-273.15
19.85°C
(b) 470k
470-273.15
196.85°C
2) Convert the following temperature to kelvin scale.
a) 25°C (b)373°C .
Ans-
(a) 25°C
=25+273.15
298.15k
(b)373°C
= 373+273.15
646.15k
3) Give Scientific reason for the following.
(a) Naphthalene balls disappear with time without leaving any solid.
Ans-Naphthalene balls evaporate directly into gas from solid. Naphthalene balls shows the property of sublimation. When heated solid particles are directly converted into vapour.
(b)We can get the smell of perfume sitting several metres away.
Ans-The particles of perfume can travel longer distance as these particles are far from each other. There force of attraction is less and hence we can smell perfume even from several metres.
4) Arrange the following substances in increasing order of force of attraction between particles.
Water, Sugar, Oxygen.
Ans- Sugar>Water> Oxygen
The force of attraction in sugar is the most ,water has less force of attraction as compared to sugar and oxygen has least force of attraction between the particles.
5) What is the physical state of water at 25°C , 0°C , 100°C
Ans- At 25°C water is in liquid state.
At 0°C water is in solid state
At 100°C water is in liquid state.
6) Give two reasons to justify.
(a) Water at room temperature is liquid.
Ans-
1) water molecules are held together by hydrogen bonds which do not break at room temperature.
2) force are strong enough which would not break at room temperature.
Therefore water is liquid at room temperature.
(b) Iron almirah is solid at room temperature.
Ans-
1) particles of iron are closely packed at room temperature.
2) The force of attraction is very strong that iron almirah is solid at room temperature.
7) Why is ice at 273 K more effective in cooling than water at same temperature?
Ans- Because ice absorbs more heat and energy at 273 Kelvin than water at 273 k. Water comparatively absorbs less heat and energy at the same temperature.Therefore ice at 273 kelvin is effective in cooling than water at 273 k.
8) What produces more severe burns boiling water or steam?
Ans-Steam will produce more severe burns than boiling water because its energy is more as compared to boiling water. It has more latent heat of vaporization than water. Thus it will produce more energy and will cause more severe burns.
9) Name A B C D E and F in the following diagram showing change in state.
Ans-
A- Fusion
B- Vaporization
C- Condensation
D- Solidification
E- Sublimation
F- Sublimation
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