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Eighth Grade (Grade 8) Matter Questions for Tests and Worksheets

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ICSE Solutions Selina ICSE Solutions Selina Class 7 Chemistry ICSE Solutions Selina Concise ICSE Solutions for Class 7 Chemistry Chapter 1 Matter and Its Composition Physics Biology Maths Geography History & Civics ML Aggarwal Solutions
APlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 7 Chemistry. You can download the Selina Concise Chemistry ICSE Solutions for Class 7 with Free PDF download option. Selina Publishers Concise Chemistry for Class 7 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

1. Matter has mass and occupies space.

2. Matter is made up of atoms and molecules.

3. Atoms are the smallest particles of matter which may or may not have independent existence.

4. Molecules are capable of independent existence. They are made up of atoms of same kind or different kinds.

5. The atoms and molecules are in random motion.

6. There are gaps between the molecules of matter called as intermolecular space.

7. There exists a force of attraction between the molecules known as intermolecular force of attraction.

8. Matter exists in three states : solids, liquid and gas.

9. Matter can change from one state to another on changing temperature and pressure.

10. The change of state of a matter from one form into another is called interconversion of states of matter.

Question 3.
If an object weighs 6 N on earth what will be its weight on moon. What will be the change in its mass?
Answer:
Weight of body on moon = th of its weight on earth.
∴ Body will weigh of 6 = x 6 = 1 N on moon
Mass of a body does not change with change in gravity. So mass of a body will remain the same on moon.

Question 4.
Write your observation and conclusion for the following:
(a) When few marbles are put in a glass half filled with water.
(b) Ice is kept at room temperature.
Answer:
(a) Take some marbles and put them into the water of glass tumbler one by one. After some time you will notice that water level crosses the mark and rises. This is because the marbles occupy space. Again weigh the glass with the marbles. You will find that the second mass is greater than the first one. This proves that, marbles have mass.

This proves that, matter has mass and occupies space.
(b) Ice when kept at room temperature again changes back into liquid water.

1. It can neither be created nor destroyed.

2. It is composed of a particular material which can either be Homogeneous or Heterogeneous.

3. Matter has, volume, mass and weight as per their state.

Answer:
Giving two examples of each type.
(a) Solid : A solid is that state of matter which has a fixed shape, mass and volume. It suffers very small changes in volume by changing the temperature. It can not be compressed,
e.g. - Sand, Wood, Copper, Ice, etc.
(b) Liquid : It has a definite mass and volume but lacks a shape of its own. It takes up the shape of the containing vessels. It can be compressed to an extents,
e.g. - Milk, water, ink, etc.
(c) Gas : It is a state of matter which has only definite mass but no definite shape and volume. It takes up the shape of the container
e.g. - Carbon dioxide, oxygen, etc.

Question 8.
Why are liquids and gases called as fluids.
Answer:
The particles are free to move in any direction i.e. they can
flow because all substances that can flow are called fluids.
Liquids and gases are fluids.

Question 9.
(a) Define interconversion of states of matter.
(b) Why do solids, liquids and gases differ in their physical state?
(c) Under what conditions do solids, liquids and gases change their state.
Answer:
(a) The process by which matter changes from one state to another and back to original state, without any change in its chemical composition.
(b)Intermolecular force of attraction.
Intermolecular spaces are two important properties of matter that account for the different states of matter.
(c) Matter can change from one state to another on changing temperature and pressure.

Question 10.
Give reasons :
(a) When a stone is dipped in a glass containning some water the level of water rises but when a spoon of sugar is added to it and stired, the water level does not rise?
(b) A drop of ink added to water in a glass turns whole water blue.
Answer:
(a) Take half a glass of water. Dip a spoon in it. What do you observe? The water level rises, indicating that spoon occupies space.

Now remove the spoon, water comes down to its original level. Now add a spoon of sugar to it and stir well. The sugar disappears but the level of water in the glass does not rise, that means the volume of water has not increased. But where did the sugar particles disappear?
The sugar particles being smaller get adjusted between the water molecules. This shows that there are intermolecular space in water.
(b) This is because tfie water as well as ink particles (molecules) are in continuous random motion. Due to motion, the blue coloured particles of the ink spreads all over and give blue colour to the water.

(a) Air is a matter because it has weight, mass and space and it can be compressed.
(b) The molecules are made up of atoms.
(c) The quantity of matter in an object is called its mass.
(d) The state of matter with definite volume and definite shape is called solid.
(e) The substances which can flow are called fluids.

Question 12.
Name the terms for the following :
(a) The change of a solid into liquid.
(b) The force of attraction between the molecules of matter.
(c) The particles of matter which may or may not have independent existence.
(d) The process due to which a solid directly changes into its vapours.
(e) The change of vapour into a liquid.
Answer:
(a) Melting.
(b) Intermolecular force of attraction.
(c) Solid.
(d) Sublimation.
(e) Condensation.

Question 13.
Classify the following into solid, liquid and gas :
Coal, kerosene, wood, oxygen, sugar, blood, water vapour, milk, wax.
Answer:

Question 4.
If an object weighs 6 kg on earth. What will be its weight on moon ?
Answer:
Weight of body on moon = th of its weight on earth
∴ Body will weigh x 6 = 1 kg on moon

Question 9.
Define:
(a) Intermolecular force of attraction.
(b) Intermolecular space.

Answer:
(a) The molecules of matter are always in motion and attract each other with a force called intermolecular force of attraction due to which they are held together.
(b) The molecules can move only when there are gaps or space between them, this space is called intermolecular space.

Question 10.
Classify the following into solids, liquids and gases.
Oxygen, milk, common salt, wax, stone, water vapour, carbon-dioxide, sugar, mercury, coal, blood, butter, copper, coconut oil, kerosene.
Answer:

Question 11.
Why do solids, liquids and gases differ in their physical states ?
Answer:

1. Intermolecular force of attraction.

2. Intermolecular spaces are two important properties of matter that account for the different states of matter.

1. Solids are hard that is, they have a definite shape and volume.

2. Solids are generally incompressible.

3. Solids are rigid, that is, they do not flow.

Question 18.
What is the relation between intermolecular space and intermolecular force ?
Answer:
The force of attraction between the molecules of a given substance is called intermolecular force and the space between these molecules is called intermolecular space.
The basic relation between the two is that they are inversely proportional to each other. More is the intermolecular force lesser is the intermolecular space and vice-versa.

1. Gases can be compressed easily :
The reason for this property of gases is that there is very large intermolecular space between gas molecules. On mere applying pressure, they are easily compressed.

2. Liquids can flow easily :
In liquids intermolecular force is weaker than that of solids. So molecules in a liquids can slip over one another and liquids can flow unlike solids.

3. We need to classify things :
We need to classify things in order to distinguish them. In this way, things can be categorized and can be easily studied.

4. Pure substances have fixed melting or boiling poin :
Pure substances consists of only one kind of matter. All the particles of a pure substance are alike. It has a definite composition and similar properties. This is the reason that pure substances have fixed melting or boiling points.

5. Electricity is not considered matter :
Electricity neither has mass nor it occupies space. Beside it can not be seen by our eyes. This is why electricity is not considered matter.

1. Matter-Anything that has mass and occupies space is called matter.

2. Intermolecular force - The force of attraction between the molecules of a given substance is called intermolecular force.

3. Element - It is defined as that pure substance which contains only one type of atoms e.g. hydrogen, chlorine.

4. Atom - An atom is the smallest part of an element that takes place in a chemical reaction.

5. Molecule - A molecule is a smallest part of a compound that exists independently.

Question 23.
Write your observation and conclusion for the following:

1. When a small stone is gently dipped into a glass filled with water.

2. When one of the balloons suspended to the metre scale is punctured while other remains inflated ?

1. You will see that some water flows out of the tumbler and collects in the bowl. Remove the stone from the tumble. The level of water in the tumbler comes down. Now, pour the water collected in the bowl back into the tumbler. The glass tumbler is filled again. This is because the stone occupied space and therefore drives the water out of the tumbler. This proves that not only solids but liquids also occupy space.

2. Take two similar balloons and inflate them equally. Suspend one balloon to the left of a metre scale and the other one to the right of it, as shown in the figure below. Balance the scale in the middle with the help of a peg.

Question 24.
How will you prove by an experiment that solids occupy space ?
Answer:
Experiment to show that solids occupy space :
Take a glass bowl. Place a glass tumbler full of water in it. Now tie a stone with thread and lower into the water. Some water flows out of tumbler into bowl. When we remove stone from tumbler the level of water in tumbler comes down. This shows that solids occupy space.

Question 25.
Name the three states of matter and define them.
Answer:
There are three states of matter
(b) Atoms and Molecules

Solid State : The molecules are very close to each other hence intermolecular spaces are small and intermolecular force is strong.

Hence solids have definite volume, rigid, retain definite shape and are incompressible.

Liquids : The molecules are less closely packed have more intermolecular spaces than solid, less stronger forces than solids.
Hence liquids have definite volume but no definite shape. They take the shape of container in which they are put.

Gases: The molecules in the gases are for apart with weakest force of attraction. Hence gases have neither definite volume nor definite shape and compressible.

1. Why do liquids and gases flow but solids do not ?
The molecules of liquids and gases are far apart i.e.
have more gaps, intermolecular attraction force is very less as compared to solids, hence liquids and gases can flow but solids do not as gaps in solid molecules is less and molecular force of attraction very strong.

2. A gas fills up the space available to it.
Intermolecular force of attraction is least and intermolecular spaces are very large, hence gases can fill up the space available to them.

3. The odour of scent spreads in a room.
Scent fumes (molecules) being gases fill the spaces between air molecules and the molecules of air fill the spaces between scent molecules due to diffusion, fumes spread into a room.
OR
Due to inter-mixing of scent molecules and air molecules, scent fumes spread into the room.

4. We can walk through air.
The molecules of air are far apart i.e. large gaps and we can walk through air easily.

5. Liquids have definite volume but no difinite shape.
The molecules of liquid are loosely packed and intermolecular force of attraction is small but number of molecules in it remain the same. Hence liquids have definite volume but no definite shape.

Question 27.
Give reasons :
(a) When a teaspoon of sugar is added to half a glass of water and stirred, the water level in the glass does not rise.
Add one teaspoon of sugar to it and stir. The sugar disappear but the level of water in the glass does not rise that means the volume of water has not increased. Because the sugar particles are adjusted between the water molecules. The shows that there are intermolecular gaps in water.

(b) When an empty gas jar is inverted over a gas jar containing a coloured gas, the gas also spreads into the empty jar.
This shows that gases can fill up all the space that they get, and they have neither a fixed shape nor a fixed volume. They have no free surfaces, either.

(c) A red ink drop added to small amount of water in a glass turns water red in some time.
If we put a drop of red ink in a glass of water, its particles diffuse with particles of water slowly but continuously and the water turns red.

Have definite volume but no

Have no definite shape or

Intermolecular force of attraction

Intermolecular force of

is weaker than that in solids

attraction is the weakest (almost negligible)

Molecules are not as tightly

Intermolecular space is the

packed as in solids and intermol

maximum and the

ecular space is more than that in solids.

molecules are far apart.

Molecules have no fixed position

Molecules move around freely

Can be compressed slightly

Can be easily compressed

Are capable of flowing

Can flow in all directions.

1. It is the smallest part of an element.

1. It is the smallest part of a compound.

2. It does not have independent existence

2. It has an independent existence.

OBJECTIVE TYPE QUESTIONS

1. Water is a matter because it has mas and occupies space.

2. Any matter which has a definite volume but no definite shape is called a liquid.

3. Fluid can flow.

4. The molecules are at a greater distance in gases compared to liquids.

5. Water boils at 100 °C.

6. The physical state of a substance, which has a fixed volume but no fixed shape is liquid.

7. All matter is made up of tiny particles called atoms.

8. Liquids have a definite Volume.

9. The temperature at which a liquid boils is called the boiling point of that liquids

10. Molecules in a solid are packed very closely.

11. Liquids have no definite shape.

12. When a gas is cooled, its molecules loose energy,

13. Matter is anything that has mass and occupies space.

I. Write whether the following statements are true or false.
(a) Only water can exist in three different states.
(b) If the container in which a gas is collected has an opening, the gas will flow out and spread itself indefinitely.
(c) Solids have the largest inter-molecular space.
(d) There is no difference between evaporation and boiling.
(e) All solids, on heating, first change to the liquid and then to the gaseous state always.
(f) The intermolecular force of attraction is the weakest in gases.
(g) A gas has no free surface.
(h) Intermolecular force of attraction is greater in gases than in liquids.
Answer:

II. Write true or false for each statement. Rewrite the false statements correctly.
(a) Matter cannot exist in different states.
(b) If the intermolecular space is more than the intermolecular force will be weaker.
(c) Solids and liquids can flow.
(d) Solids can be compressed easily.
(e) The smallest part of an ^element capable of independent existence is called an atom.
(f) The intermolecular space in a gas is almost negligible.
Answer:
(a) False. Matter can exist in different states.
(b) True.
(c) False. Gases and liquids can flow.
(d) False. Solids cannot be compessed easily.
(e) True
(f) False. The intermolecular space in a gas is very large.

Question 3.
For each of the following statements, say whether it describes a solid, a liquid or a gas.
(a) Particles move about very quickly Liquid
(b) Particles are quite close together Solid
(c) Particles are far apart and move in all directions Gas

1. Formation of water vapour from water is vaporation.

2. Disappearance of camphor is sublimation.

3. Conversion of ice into water is melting.

4. Conversion of water into steam is boiling.

Question 6.
Give two examples for each of the following :
(a) Substances which sublime.
Naphthalene, camphor, dry ice.

(b) Substances which do not change their states.
Paper, sugar.

(c) Substances which are rigid and not compressible.
Glass, stone, pen.

MULTIPLE CHOICE QUESTIONS

The state of matter which has no definite shape or volume is called
Answer:

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Selina Concise Chemistry Class 7 ICSE Solutions - Matter and Its Composition - A Plus Topper

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Selina Concise Chemistry Class 7 ICSE Solutions - Matter and Its Composition ICSE SolutionsSelina ICSE SolutionsML Aggarwal Solutions APlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 7 Chemistry. You can download the Selina Concise Chemistry ICSE Solutions for Class 7 with Free PDF download option.

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PROPERTIES OF MATTER

WHAT IS MASS?

MASS is the amount of matter in a physical body. The standard unit of mass is the kilogram (kg). We can measure the mass with instruments, like scales and weighing machines.

Mass and weight video

WHAT IS VOLUME?

VOLUME is the amount of space that a body occupies. We measure the volume in cubic metre (mᶾ) =1000 litres.

We can measure the volume of a solid body by putting it into a beaker of water. The body displaces some of the water and makes the water level rise. This change in the water level is equal to the volume of the solid body.

Volume video

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Introduction-

Matter is the basic structure of which all materials, living or non living are made of.

Matter is anything that - occupies space, has mass & perceived by the senses.