ICSE Living Science Chemistry for Class 6 Solutions Chapter 2 States of Matter

Check Your Progress

State if the following statements are true or false. Correct the statement if it is false.
Question 1.
Air is matter.
Answer:
True

Question 2.
The amount of space occupied by matter is called its density.
Answer:
False. The amount of space occupied by matter is called its volume.

Question 3.
Solids have a definite volume and a definite shape.
Answer:
True

Question 4.
Liquids can flow better than gases.
Answer:
False. Gases can flow better than liquids.

Question 5.
In liquids, the intermolecular space is the largest.
Answer:
False. In gases, the intermolecular space is the largest.

A. Tick the most appropriate answer.

Question 1.
The intermolecular force of attraction is maximum in –
a. solids
b. liquids
c. gases
d. both a. and c.
Answer:
a. solids

Question 2.
The intermolecular space is minimum in –
Answer:
a. solids
b. liquids
c. gases
d. both a. and c.
Answer:
c. gases

Question 3.
Fluidity is maximum in –
a. solids
b. liquids
c. gases
d. both a. and c.
Answer:
c. gases

Question 4.
Gases
a. cannot be compressed easily
b. occupy the entire space of the container
c. have a definite shape
d. cannot flow
Answer:
b. occupy the entire space of the container

Question 5.
Evaporation of a liquid occurs at any temperature below its
a. freezing point
b. boiling point
c. melting point
d. none of these
Answer:
b. boiling point

B. Fill in the blanks.
1. Matter occupies ………… and has …………
Answer:
Matter occupies space and has mass.

Question 2.
A …………. is the smallest particle of a substance which can exist independently.
Answer:
A molecule is the smallest particle of a substance which can exist independently.

Question 3.
Liquids have no definite …………
Answer:
Liquids have no definite shape.

Question 4.
When a gas is cooled, its molecules ………………. energy
Answer:
When a gas is cooled, its molecules lose energy

Question 5.
The process of a liquid changing to vapour at any temperature below its boiling point is called ………………
Answer:
The process of a liquid changing to vapour at any temperature below its boiling point is called evaporation.

Question 6.
The temperature at which a liquid freezes to become a solid is called its …………. point.
Answer:
The temperature at which a liquid freezes to become a solid is called its freezing point.

Question 7.
…………… is a process by which a substance directly changes from the solid to the gaseous state without going through the liquid state.
Answer:
Sublimation is a process by which a substance directly changes from the solid to the gaseous state without going through the liquid state.

C. State if the following statements are true or false. Correct the statement if it is false.

Question 1.
Matter cannot exist in different states.
Answer:
False. Matter can exist in different states.

Question 2.
The intermolecular force of attraction is the weakest in gases.
Answer:
True

Question 3.
Solids can diffuse.
Answer:
False. Solids cannot diffuse.

Question 4.
Liquids do not have a definite shape but have a definite volume.
Answer:
True

Question 5.
Liquids are highly compressible.
Answer:
False. Gases are highly compressible.

Question 6.
The molecules in a gas move about in all directions at a high speed.
Answer:
Time

Question 7.
The interconversion of states of matter involves a change in the mass or composition of the substance.
Answer:
False. The interconversion of states of matter does not involve a change in the mass or composition of the substance.

D. Name the following.

Question 1.
Space between the molecules of matter.
Answer:
Intermolecular space

Question 2.
The intermixing of particles of different substances on their own
Answer:
Diffusion

Question 3.
Change of a solid to a liquid
Answer:
Melting or fusion

Question 4.
Change of a liquid to a gas
Answer:
Boiling or vaporization

Question 5.
Change of a solid to a gas
Answer:
Sublimation

E. Answer the following in short.

Question 1.
Why do solids lack the property of diffusion ?
Answer:
Due to strong intermolecular force of attraction, the molecules of solids do not leave their fixed positions to move away from one another.Therefore, solids do not diffuse.

Question 2.
What is interconversion of states of matter ?
Answer:
The process of change of matter from one state to another and then back to the original state is called the interconversion of states of matter.

Question 3.
What happens to the molecules of a solid when it is heated ?
Answer:
When a solid is heated, its molecules gain energy and become very active. They try to overcome the intermolecular forces of attraction. So they vibrate faster and start to move and the intermolecular space between them increases. If the temperature continues to increase, at a certain point, the intermolecular space between the molecules of the solid increases to an extent that it changes into a liquid.

Question 4.
What happens to the molecules of a gas when it is cooled ?
Answer:
When a gas is cooled, its molecules lose energy and slow down. As a result, the intermolecular forces of attraction between them increase and they come close together. With continued cooling the intermolecular spaces decrease to such an extent that a gas changes to a liquid.

Question 5.
What is vaporization ?
Answer:
The process of conversion of a liquid, into vapour (or gas) on heating is called boiling or vaporization.

F. Answer the following in detail.

Question 1.
Give a simple experiment to show that matter occupies space.
Answer:
Aim : To show that matter occupies space
Materials Required : A glass tumbler, water, a stone, a piece of thread, a glass bowl Procedure:
1. Take a glass tumbler and place it in a bowl. Pour water gently in the tumbler so that it is completely filled.
2. Now take a small stone. Tie it with a piece of thread and lower this stone gently into the tumbler. What do you observe?
3. Remove the stone from the glass tumbler. See the level of the water in the tumbler. Now pour the water collected in the bowl into the tumbler. What do you observe ?

Observations :
1. When the stone is lowered into the glass tumbler filled completely with water, some water overflows from the glass tumbler and collects in the bowl (figure b).
2. When the stone is removed from the glass tumbler and the water collected in the bowl is poured back into the tumbler, the water fills have glass tumbler up to the brim again (figure d).

Conclusion : From the above observations, we conclude that matter occupies space. The stone occupies space and hence pushes the water out of the tumbler. Water is matter too and also occupies space. This is observed when it fills the tumbler up to its brim.
Living Science Chemistry Class 6 ICSE Solutions Chapter 2 States of matter - 1

Question 2.
Give a simple experiment to show that matter has mass.
Answer:
Aim : To show that matter has mass Materials Required : A spring balance, cotton thread, a small empty can, water, pebbles or sand

Procedure :

  1. Suspend the spring balance from a hook. The reading of the pointer should read O.
  2. Take an empty can and tie it to a piece of strong cotton thread to make a suspension loop. Now suspend the can from the hook of the spring balance.
  3. Note the reading of the pointer.
  4. Now pour some water into the can. What do you observe ?
  5. Repeat the experiment using sand or pebbles in the can. What do you observe ?
  6. Note the reading of the pointer each time.

Observation :
Record your observations as follows:

  1. Object
  2. Initial reading of the pointer
  3. Final reading of die pointer
  4. Difference in the final and initial reading of the pointer.

Conclusion:
The difference between the final and the initial reading of the pointer gives the weight of the things put in the can. Thus, from above Activity, we conclude that matter has mass.
Living Science Chemistry Class 6 ICSE Solutions Chapter 2 States of matter - 2

Question 3.
Write the general properties of solids.
Answer:
Properties of solids :

  1. Solids have a definite shape and a definite volume.
  2. Solids are incompressible.
  3. Solids have a high density.
  4. Solids do not diffuse.

Question 4.
Write the general properties of liquids.
Answer:
Properties of liquids :

  1. Liquids do not have a definite shape but have a definite volume.
  2. Liquids have a tendency to flow (fluidity)
  3. Liquids cannot be compressed much.
  4. Liquids have less density as compared to solids.
  5. Liquids can diffuse.

Question 5.
Write the differences between boiling and evaporation.
Answer:
Boiling :

  1. Boiling occurs only at a given temperature known as the boiling point of the liquid.
  2. Boiling occurs throughout the bulk of the liquid.
  3. Boiling is a fast process.
  4. No cooking is caused during boiling.
  5. Boiling occurs only when the liquid is heated.

Evaporation :

  1. Evaporation takes place at any temperature below tire boiling point of the liquid.
  2. Evaporation takes place only from the surface of the liquid.
  3. Evaporation is a slow process.
  4. Cooling is always caused during evaporation.
  5. Evaporation of a liquid takes place on its own.

G. Give reasons for the following.

Question 1.
Electricity is not considered matter.
Answer:
It is because it has neither mass nor does it occupy space.

Question 2.
Liquids can flow.
Answer:
A liquid generally flows because its particles are able to slide, slip and glide over one another due to the weak intermolecular force of attraction.

Question 3.
Gases have no definite shape or volume.
Answer:
The intermolecular space in gases is maximum and there is negligible intermolecular force of attraction. So the molecules move about freely all around in a closed container and fill the entire space, irrespective of its shape or size. Thus, gases take the shape and volume of the container they occupy.

Question 4.
Gases can be compressed easily.
Answer:
Since there is a lot of empty space between the molecules of a gas, they can be easily compressed.

Question 5.
We can smell a perfume from several metres away.
Answer:
It is because the gases diffuse very rapidly. The particles in gases move very quickly in all directions because of very weak intermolecular force of attraction. Due to this random motion, the particles of one gas (perfrume) readily move into the space between the particles of another gas (air). Hence, we can smell a perfume from several metres away.

Skill-Based Question

Name A, B, C, D and E in the following diagram showing changes in the state of matter.
Living Science Chemistry Class 6 ICSE Solutions Chapter 2 States of matter - 3
Answer:
A → Melting or fusion on heating
B → boiling or vaporization on heating
C → Condensation on cooling
D → Solidification or freezing on cooling
E → Sublimation on heating

Living Science Chemistry Class 6 ICSE Solutions

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