THESE NOTES ARE PREPARED ACCORDING TO JKBOSE SYLLABI IN SIMPLIFIED AND CONCISE PATTERN
Matter is everything that has mass and occupies space.
The Characteristics of matter are as follows:
1. Particles of matter has large spaces inbetween them.
2. Particles of matter are continuously moving.
3. Particles are matter attract each other.
Q. A diver is able to cut through water? What property of matter does this observation show?
Ans. The particles of matter attract each other. In liquids the force of attraction is very less than solids, Hence diver is able to cut through water.
Q. What are the Characteristics of different states of matter?
Ans: Generally there are three states of matter, i.e, Solids, Liquids and Gases.
A. The Solid State:
1. They have fixed shape and definite volume
2. The dont diffuse into each other
3. They have limited compressibility e.g, Book, Sponge, Rock
B. The Liquid State:
1. They do not have fixed shape but have definite volume.
2. They are not diffusible, but other substances diffuse into it.
3. They do not compress e.g, Water, Honey
C. The Gaseous State:
1. They neither have fixed shape nor definite volume
2. They are highly diffusible.
3. They are highly compressible e.g, Oxygen, LPG
Q. Why Ice floats on Water?
Or
Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why.
Ans: Normally liquids have lower density than solids. However Water has Unique Properties. The water with temperature 4°C is more dense than Ice with temperature 0°C. Hence Ice floats on water.
Q. Define Latent heat of Fusion?
Ans: The amount of heat energy required to change 1 Kilogram of solid into liquid at melting point is latent heat of fusion.
When solid melts, the temperature doesn't change till all particles get converted into liquid.
Q. What is latent heat of vapourization?
Ans: The amount of heat required to change 1 litre of liquid into gas at boiling point is called latent heat of vapourization.
At boiling point the particles break from forces of attraction.
Q. What is sublimation?
Ans: The conversion of solid directly into gas is called sublimation e.g Camphor, Napthelene.
Q. Convert the following temperatures into celcius scale.
1. 300° Kelvin : 27°C
2. 273° Kelvin : 0°C
3. 573°Kelvin: 300°C
Q. Suggest methods to Liquify atmospheric gases?
Ans: The atmospheric gases can be liquified by the process of condensation under high pressure or lowering temperature.
Q. What is Evaporation? How does it cause cooling?
What are the factors that affect rate of evaporation?
Ans: Evaporation is the process of conversion of liquid directly into vapours at any temperature below the boiling point.
It occurs because particles at surface have higher kinetic energy to escape forces of attraction.
The rate of evaporation depends on following factors:
1. It increases with increase in surface area.
2. It increases with increase in temperature.
3. It increases with increase in wind speed.
4. It decreases with increase in humidity.
Q. What type of clothes should we wear in summer?
Ans: We should wear cotton clothes in summer as cotton is good absorber of water and helps in absorbing and evaporating sweat faster.
Q. Why desert cooler cool better on the dry day?
Ans: The air around us cannot hold more than a definite amount of water vapour which is defined as humidity. On dry day there is less humidity, so more sweat is lost from the body into air.
Q. Which causes severe burning, Steam or Hot water?
Ans. The steam causes severe burning because its temperature is more that that of boiling water due to latent heat of vapourization.
Q. Define Latent heat of Fusion?
Ans: The amount of heat energy required to change 1 Kilogram of solid into liquid at melting point is latent heat of fusion.
When solid melts, the temperature doesn't change till all particles get converted into liquid.
Q. What is latent heat of vapourization?
Ans: The amount of heat required to change 1 litre of liquid into gas at boiling point is called latent heat of vapourization.
At boiling point the particles break from forces of attraction.
Q. What is sublimation?
Ans: The conversion of solid directly into gas is called sublimation e.g Camphor, Napthelene.
Q. Convert the following temperatures into celcius scale.
1. 300° Kelvin : 27°C
2. 273° Kelvin : 0°C
3. 573°Kelvin: 300°C
Q. Suggest methods to Liquify atmospheric gases?
Ans: The atmospheric gases can be liquified by the process of condensation under high pressure or lowering temperature.
Q. What is Evaporation? How does it cause cooling?
What are the factors that affect rate of evaporation?
Ans: Evaporation is the process of conversion of liquid directly into vapours at any temperature below the boiling point.
It occurs because particles at surface have higher kinetic energy to escape forces of attraction.
The rate of evaporation depends on following factors:
1. It increases with increase in surface area.
2. It increases with increase in temperature.
3. It increases with increase in wind speed.
4. It decreases with increase in humidity.
Q. What type of clothes should we wear in summer?
Ans: We should wear cotton clothes in summer as cotton is good absorber of water and helps in absorbing and evaporating sweat faster.
Q. Why desert cooler cool better on the dry day?
Ans: The air around us cannot hold more than a definite amount of water vapour which is defined as humidity. On dry day there is less humidity, so more sweat is lost from the body into air.
Q. Which causes severe burning, Steam or Hot water?
Ans. The steam causes severe burning because its temperature is more that that of boiling water due to latent heat of vapourization.
Q. Tabulate the differences in the characteristics of
states of matter.
Ans:
|
Solids |
Liquids |
Gases |
|
They have
definite shape and Volume |
They do not
have definite shape and volume |
They do not
have definite shape and volume |
|
They are most
dense |
Their density
is less than solids |
They are
least dense |
|
They have
very less kinetic energy |
Their kinetic
energy is more than solids but less than gases |
They have
maximum kinetic energy |
Q. Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.
Ans:
Rigidity: Rigidity is the ability of an object to maintain shape and volume. Solids are more rigid than liquids and gases.
Compressibility: Compressibility is the ability of an object to reduce in volume when force is applied.
Fluidity: Fluidity is the ability of matter flow. Liquids and gases have fluidity and are called fluids.
Filling a gas container: Filling a gas container means attaining the shape of the container in which the matter is kept. e.g. Liquids attain the shape of the container in which it is kept.
Shape: Shape means physical form of matter with a definite boundary. Solids have definite shape.
Kinetic energy: Kinetic energy is the energy possessed by the particles of matter due to their motion. Gases have more kinetic energy than liquids and solids.
Density: Density means mass of the matter per unit volume. Solids have more density than liquids and gases.
Q. Give reasons:
(a) A gas fills completely the vessel in which it is kept.
Ans: A gas completely fills the vessel in which it is kept because its particles have more kinetic energy and least forces of attraction.
(b) A gas exerts pressure on the walls of the container.
Ans: A gas exerts pressure on the walls of container because its particles have more kinetic energy and least forces of attraction.
(c) A wooden table should be called a solid.
Ans: A wooden table has definite shape and volume. It is rigid and cannot be compressed. Hence, it is 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: Air particles have not only large spaces in between them but also have less force of attraction than solids. Hence, we can easily move our hand in air but not in solids.
Q. What is the physical state of water at: a. 250C b. 100C?
Compressibility: Compressibility is the ability of an object to reduce in volume when force is applied.
Fluidity: Fluidity is the ability of matter flow. Liquids and gases have fluidity and are called fluids.
Filling a gas container: Filling a gas container means attaining the shape of the container in which the matter is kept. e.g. Liquids attain the shape of the container in which it is kept.
Shape: Shape means physical form of matter with a definite boundary. Solids have definite shape.
Kinetic energy: Kinetic energy is the energy possessed by the particles of matter due to their motion. Gases have more kinetic energy than liquids and solids.
Density: Density means mass of the matter per unit volume. Solids have more density than liquids and gases.
Q. Give reasons:
(a) A gas fills completely the vessel in which it is kept.
Ans: A gas completely fills the vessel in which it is kept because its particles have more kinetic energy and least forces of attraction.
(b) A gas exerts pressure on the walls of the container.
Ans: A gas exerts pressure on the walls of container because its particles have more kinetic energy and least forces of attraction.
(c) A wooden table should be called a solid.
Ans: A wooden table has definite shape and volume. It is rigid and cannot be compressed. Hence, it is 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: Air particles have not only large spaces in between them but also have less force of attraction than solids. Hence, we can easily move our hand in air but not in solids.
Q. What is the physical state of water at: a. 250C b. 100C?
Ans: Water exists in gaseous form both at 250 C & 100C.
Q. For any substance, why does the temperature remain constant during the change of state?
Ans: During the change of state, the heat is used to break the bonds of attraction of the molecules. This is called latent heat of fusion and latent heat of vaporization.
Q. How does the water kept in an earthen pot (matka) become cool during summer?
Ans: The water kept in an earthen pot becomes cool during summer due to evaporation through the tiny pores of Matka. The evaporating water takes away the latent heat due to this process. This creates a cooling effect in the pot which keeps the rest of the water cool.
Q. Why does our palm feel cold when we put some acetone or petrol or perfume on it?
Ans: When we put some acetone or perfume on our palm, it starts evaporating. During evaporation, particles of the liquid absorb energy from the surface of the palm to compensate for the loss of energy, making our palm feel cold.
Q. Why are we able to sip hot tea or milk faster from a saucer rather than a cup?
Ans: The saucer has large surface area than a cup which helps in loss of heat from hot tea or milk to the surroundings easier. Hence, we are able to sip hot tea faster from saucer.
Q. Convert the following temperatures to the Celsius scale. (a) 293 K (b) 470 K
Ans: a) 293 K = 20 C b) 470 K = 197 C
Q. Convert the following temperatures to the kelvin scale. (a) 25 °C (b) 373 °C
Ans: (a) 25 °C = 298 K (b) 373 °C = 646 K
Q. Give reason for the following observations.
(a) Naphthalene balls disappear with time without leaving any solid.
Ans: Naphthalene ballas undergo sublimation. During this process, the naphthalene directly converts to gas with out leaving any solid.
Other substances that undergo sublimation are Camphor, Dry ice etc.
(b) We can get the smell of perfume sitting several metres away.
Ans: The Kinetic energy of particles in perfume is high and they diffuse quickly to the sorroundings. Hence, we can smell it sitting several meters away.
Q. Arrange the following substances in increasing order of forces of attraction between the particles— water, sugar, oxygen.
Ans: Solids have more force of attraction than liquids which have more attraction than gases.
Hence, Oxygen < Water < Sugar
Q. What is the physical state of water at— (a) 25 °C (b) 0 °C (c) 100 °C ?
Ans:
(a) 25°C: At 25°C, Water is in liquid state.
(b) 0°C: At 0°C, Water is Solid state.
(c) 100°C: At 100°C, Water is in gaseous state.
Q. Give two reasons to justify—
(a) water at room temperature is a liquid.
Ans: Water is liquid at room temperature as it does not possess definite shape and volume at that temperature. It also moves freely.
(b) an iron almirah is a solid at room temperature.
Ans: Solid almirah is solid at room temperature as it possesses definite shape and volume at that temperature. It also has fixed shape.
Q. Why is ice at 273 K more effective in cooling than water at the same temperature?
Ans: At 273 K, the ice molecules absorb heat from the surroundings and uses it to break bonds due to latent heat of fusion. Water on the other hand absorbs less heat from the surroundings. Hence, ice is more effective in cooling than water at 273 K.
Q. Name A, B, C, D, E and F in the following diagram showing change in its state:
Ans:
.png "Name A, B, C, D, E and F in the following diagram showing change in its state:")
...................................
