Class-7 Dalal Simplified Matter and Its Composition ICSE Chemistry Solutions

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Class-7 Dalal Simplified Matter and Its Composition ICSE Chemistry Solutions Dr Viraf J Dalal Middle School Allied Publishers Solutions. Chapter-1. We Provide Step by Step Solutions of Exercise/Lesson -1 Elements Compound and Mixtures with Objective Type Questions, Fill in the blanks and Give reason , Match the following of Dr Viraf J Dalal Middle School Chemistry Allied Publishers. Visit official Website CISCE for detail information about ICSE Board Class-7.

Class-7 Dalal Simplified Matter and Its Composition ICSE Chemistry Solutions Chapter-1

EXERCISE-1

Question 1.
Explain the meaning of the term matter with special reference to the term ‘substance’.
Answer 1:
A basic substance which makes up all the materials, living or nonliving are made is called matter.

Question 2.
Name the three states of matter. On what basis are the three states classified.
Answer 2:
Three states of matter are given below:

Solid
Liquid
Gases

Basis of the classification of Three states of matter depend upon:
Compressibility

rate of diffusion

Volume

Shape

Rigidity

Density

Arrangement of particles.

force of attraction

Question 3.
Each of the three states of matter has mass. Explain with the help simple experiments – that each state of matter has mass.
Answer 3:

(a) Solid :

A solid is placed on one side of a ruler, which makes the scale tilt on that side.

It can be concluded that solid has mass which makes the scale tilt downward.

(b) Liquid :

A glass full of water is placed on one side of a ruler, which makes the scale tilt on that side.

It can be concluded that liquid has mass which makes the scale tilt downward.

An inflated balloon filled with gas is placed on one side of a ruler, which makes the scale tilt on that side.

It can be concluded that gases have mass which makes the scale tilt downward.

Question 4.
A measuring cylinder is filled with water to a particular mark. A piece of solid is immersed inside the measuring cylinder. State why the level of water in the measuring cylinder will rise up. If the solid is removed, what will be the new level of the water in the measuring cylinder. Give a reason for your answer.
Answer 4:

When the solid is immersed in the cylinder filled with water, the water level rises up.

When the solid is removed, the water level will fall to as it was before the solid is immersed.

This experiment shows that when a solid is immersed it pushes water upwards by occupying the space of water.

It can be concluded that all solids occupy space.

Question 5.
A glass beaker is half filled with water and an empty glass tumbler is inverted & lowered inside the glass beaker. State your observations on tilting the tumbler below the level of the water in the glass beaker. Give a reason for your answer.
Answer 5:
(1) The empty glass tumbler contains air which is inverted and lowered inside the glass beaker filled with water.

(2) When this empty tumbler is tilted, the air inside the tumbler comes out and bubbles of air are seen. The air inside the tumbler was occupying space inside the beaker.

(3) This proves that gases occupy space

Question 6.
Differentiate the general properties of solids, liquids and gases in the form of a table — with reference to

(a) Mass

(b) Space

(d) Shape

(e) Compressibility

(f) Density

(g) Free surfaces

(h) Diffusion

Answer 6:

Basis	Solid	Liquid	Gas
Mass	have mass.	have mass.	have mass.
Space	occupy space.	occupy space.	occupy space.
Volume	definite volume.	definite volume.	have no definite volume.
Shape	definite shape.	no definite shape.	have no definite shape.
Compressibility	no compressibility.	slight compressibility.	high compressibility.
Density	have high density.	less density.	least density.
Free surfaces	have any number of free surfaces.	one free surface.	no free surface
Diffusion	They have no diffusibility.	Slight diffusion	high diffusibility.

Question- 7.

State in which of the three states of matter-
(a) Are the atoms or particles far apart
(b) The space between the particles is minimum.
(c) The force of attraction between the particles is very weak.
(d) The movement of the particles are neither about their own positions nor in any random direction.
Answer 7:

(a) Gas

(b) Solid

(d) Gas

Question-8

Give a reason why –
(a) Solids have a definite volume & a definite shape.
(b) Liquids have a definite volume but no definite shape.
(c) Gases have no definite volume and no definite shape.
Answer 8:

(a) Solids have definite shape and definite volume because the molecules in solid are closely packed and in fixed positions. The molecules can vibrate but do not move around which keeps the shape and volume definite.

(b) Liquids have no definite shape but definite volume because the molecules in liquid are not so closely packed and they have space between them. The molecules can move around and the forces of attraction between molecules is less as compared to solids, so the liquid takes the shape of the container and volume is definite.

(c) Gases do not have a definite shape or volume because the molecules in gases are very loosely packed, they have large intermolecular spaces and hence they move around. The force of attraction between molecules is also very less, as a result gases acquire any shape or any volume.

Question 9.
Particles of matter possess energy due to their random motion. Compare the particles in a solid, -liquid & in a gas with reference to the amount of kinetic energy possessed by each.
Answer 9:

Energy possessed by particles due to motion is kinetic energy.

Particles of solid cannot move around because they are closely packed, hence they have least kinetic energy.

Particles of liquid are less closely packed, so they move around and hence have large kinetic energy.

Particles of gases are very loosely packed, they move around continuously and hence they have very large kinetic energy.

Question 10.

Describe simple experiments to show that –
(a) particles of matter have inter molecular attraction
(b) particles of matter are closely packed in solids and less in liquids.
Answer 10:

(a) To show – Particles of matter have intermolecular attraction.

Experiment – Mercury globules are placed in a petri dish and kept apart. The petri shakes slowly and mercury globules come together to for a big globule.

The formation of big globules shows that forces of attraction exist between the molecules.

(b) To show – Particles of matter closely packed in solids and less in liquids.

Experiment – A measuring cylinder with 100ml of water is taken and solid sugar crystals are added to it. The solution is stirred carefully to form a sugar solution.

It is observed that volume of water does not change which shows that sugar fills up the intermolecular spaces between water molecules. Hence the water level does not change proving that the intermolecular spaces are more in liquids as compared to solids.

Question 11.

A crystal of iodine is placed in a closed flat bottom flask and heated. State how you would conclude from the observations seen, that inter particle space is minimum in solids and maximum in gases.
Answer 11:

A crystal of iodine is heated in a closed flask and occupies only the space at the bottom of the flask. After heating, the crystal of iodine converts into vapour and fills the whole flask with iodine vapours.

This shows that particles of solid are closely packed and occupy less space while particles of gases are loosely packed and occupy the complete space available.

Question 12.
Explain the term ‘inter conversion of matter’ – with ice as a starting material. State the term which refers to the conversion of a substance on heating from.
(a) solid state to liquid state
(b) liquid state to vapour state
(c) vapour state to liquid state
(d) liquid state to solid state.
Answer 12:

When the state of matter changes to the other and then back to the original state without changing chemical composition, it is call ‘inter conversion of matter’.

The terms which refers to the conversion of a substance are :

(a) Melting

(b) Vaporisation

(d) Solidification

Question 13.
Give a reason why solids and liquids co-exist at their melting points.
Answer 13:
A substance is in solid state before melting and in liquid state after melting. The point at which the solid turns liquid is melting point and they coexist at this point.

Objective Type Questions

Class-7 Dalal Simplified Matter and Its Composition ICSE Dr Viraf J Dalal Middle School Allied Publishers Solutions. Chapter-1.

Question 1.
Match the characteristics of the three states of matter in List I with their correct answer from List II.

List I	List II
1. Have no definite shape, volume or free surface	A. Solids only
2. Are highly compressible and less rigid	B. Liquids only
3. Have a definite volume, no definite shape and are slightly diffusible	C. Gases only
4. Are not compressible and have no diffusibility	D. Liquids and gases only
5. Have mass and occupy space	E. Solids and gases only
	Solids, liquids and gases

Answer 1:

List I	List II
1. Have no definite shape, volume or free surface	D. Liquids and gases only
2. Are highly compressible and less rigid	C. Gases only
3. Have a definite volume, no definite shape and are slightly diffusible	B. Liquids only
4. Are not compressible and have no diffusibility	A. Solids only
5. Have mass and occupy space	F. Solids, liquids and gases

Question 2.
Select the correct answer from the choice in bracket to complete each sentence:

Matter is defined as anything that occupies _______ and has _______
The three states of matter are classified on the basis of differences of certain _______ .
Matter made up of one kind of particles is said to be _______ .
Particles in a gas possess _______ kinetic energy.
The intermolecular force of attraction is _______ in solids.

Answer-2

Matter is defined as anything that occupies space and has mass
The three states of matter are classified on the basis of differences of certain physical.
Matter made up of one kind of particles is said to be homogeneous.
Particles in a gas possess very large kinetic energy.
The inter molecular force of attraction is maximum in solids.

Question 3.

Give reasons for the following.

Gases have no definite shape or volume.
Liquids have one free upper surface only.
Globules of mercury kept in a petri dish, which is shaklen slowly, come together forming a big globule.
A crystal of iodine on slow heating in a closed flask, turns into vapours and fills the complete flask.
An empty tumbler lowered into a glass beaker containing water, on tilting shows bubbles of air coming out, but when not tilted, no bubbles are seen.

Answer 3:

Gases do not have a definite shape or volume because the molecules in gases are very loosely packed, they have large intermolecular spaces and hence they move around. The force of attraction between molecules is also very less, as a result gases acquire any shape or any volume.
Liquids have one free surface because they do not have a definite volume but a shape bounded by the container they are in, so the top surface of the container is the only free surface it has.
The formation of big globules is because of the forces of attraction existing between the molecules.
The particles of solid are closely packed and occupy less space while particles of gases are loosely packed and occupy the complete space available.
When the empty tumbler is tilted, the air inside the tumbler comes out and bubbles of air are seen. The air inside the tumbler was occupying space inside the beaker. When the tumbler is not tilted, the air inside does not come out, hence no bubbles are seen.

Question 4.

State the correct term from A, B, C, D, E or F in List II which represents the – change of state of matter or its relevant property from List I

List I	List II
1. Solid ‘X’ to a liquid ‘Y’	A. liquefaction
2. Liquid ‘Y’ to its vapour ‘Z’	B. Vaporization
3. ‘Z’ to ‘Y’	C. Melting
4. ‘Y’ to ‘X	D. Solidification
5. The temperature at which ‘Y’ changes to ‘Z’	E. Melting point
	F. Boiling point

Answer 4:

List I	List II
1. Solid ‘X’ to a liquid ‘Y’	C. Melting
2. Liquid ‘Y’ to its vapour ‘Z’	B. Vaporization
3. ‘Z’ to ‘Y’	A. liquefaction
4. ‘Y’ to ‘X	D. Solidification
5. The temperature at which ‘Y’ changes to ‘Z’	F. Boiling point

Question 5.
Match the arrangement of atoms in the three states of matter in List I with the correct state in List II.

List I	List II
1. Arrangement of atoms, very closely packed	A. Solids
2. Interparticle space is maximum	B.Liquids
3. Force of attraction between particles is very weak	C. Gases
4. Movement of particles is about their own position
5. Particles in the state of matter are slightly compressible and not closely packed

Answer 5:

List I	List II
1. Arrangement of atoms, very closely packed	A.Solids
2. Interparticle space is maximum	C. Gases
3. Force of attraction between particles is very weak	C. Gases
4. Movement of particles is about their own position	A.Solids
5. Particles in the state of matter are slightly compressible and not closely packed	B.Liquids

.– : End of Matter and Its Composition Class-7 Dalal Simplified Solutions :–

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