Class 9 Science Chapter 1 Important Questions

Class 9 Science Chapter 1 Important Questions of Matter in our surroundings. Class 9 Science Chapter 1 Extra questions contains all the short and long answer questions of 9th with complete explanation. These questions are helpful for school tests as well as terminal exams. These important extra practice questions provide a complete revision of class ix science chapter 1. Frequently asked questions includes the questions asked in various public schools, kendriya vidhyalaya and government schools exams papers. After completing the chapter from NCERT Book, these extra questions will help in revision as well as to understand all the concepts of chapter properly.

These questions are useful for UP Board, MP Board, Gujrat board, Uttarakhand and all other boards who are using NCERT Textbooks for their course.

Page Contents

Class 9 Science Chapter 1 Important Extra Questions

Class: 9Science
Contents:Important Questions with answers
Chapter: 1Matter in our surroundings

9th Science Chapter 1 Extra Question Answers for 2020-2021

Important Extra questions for class 9 science chapter 1 Matter in our surroundings are given below. These questions are useful for class test as well as final exams. UP Board students are also using NCERT Books 2020-2021 for their exams, so UP Board students also take the benefits of these questions for their studies as well as for revision for exams.

Class 9 Science Chapter 1 Important Extra Questions Set – 1

Write the different properties of particles of matter?

The properties of particles of matter are:
(i) The particles of particles matter attract to each other.
(ii) The particle of matter continuously moving.
(iii) The particle of matter has space between them.

Define matter?

Anything that has mass and volume and made up of very small particle is called matter.

Write the SI units of mass, volume, temperature, work, density?

(i) Mass = 1kg
(ii) Volume = m3
(iii) Temperature= kelvin
(iv) Work = Joule
(v) Density = (mass )/volume = kgm^(-3)

What is diffusion?

The intermixing of particle of two different types of matter on their own is called diffusion. The rate of diffusion increases on increasing the temperature of diffusing substance. Diffusion is a natural process. It takes place in solid, liquid and gas.

What is fusion?

The process of melting of solid and it will become change into liquid is known as fusion.

Properties of Solids

    • They have fixed shape and volume.
    • They are rigid.
    • They do not flow.
    • They have negligible compressibility.




Class 9 Science Chapter 1 Important Extra Questions Set – 2

What are the characteristic of particle of matter?

(a) Particles of matter attract each other because of force of attraction:
(i) The force of attraction between particle of matter keep the particles bonded together. The force of attraction between particles of solid is greatest, between particles of liquid is moderate and between particles of gas is lowest.
(ii) Because of the lowest force of attraction between particles of gas we can move our hand through air easily. To move our hand in water we have to apply some force, but from a solid such as wood, we cannot move our hand.
(iii) This is because the force of attraction between particles of gas is almost negligible, in liquid the force of attraction is moderate but is greatest in solid.
(iv) The force of attraction between particle of solid, liquid and gas can be arranged in decreasing order as follows solid, liquid and gas.
(a) Particles of matter have space between them:
(i) Gas can be compressed a lot because of the space between their particles.
(ii) When sugar is dissolved in water the particle of sugar disappears in water. This happen because particles of sugar get adjusted in the space between particles of water. Additionally, you will notice that there is no rise of water level take place when one or teaspoon of sugar is added in a glass of water and this is because particles get adjusted in the space between the particle of water and no rise in the water level comes in result.

What is melting point of solid?

The minimum temperature at which solid start melting to become a liquid at the atmospheric pressure is called melting point of solid. The melting point of ice is 273.13K.

What is the boiling point of water?

The temperature at which a liquid starts boiling at the atmospheric pressure is known as boiling point. It’s boiling point is 100C or 373K.

What is the latent heat of fusion and also explain the latent heat of vaporization?

The heat energy required to convert 1 kilogram of a solid into liquid at atmospheric pressure at its melting point. This is known as the latent heat of fusion.

What is latent heat of vaporization?

The particles in the steam have observed extra energy and their energy is called the latent heat of fusion.

Properties of liquids

    • They have fixed volume but no fixed shape.
    • They have more compressibility than solids.
    • They from up to down.
    • It’s particles are loosely packed.

Class 9 Science Chapter 1 Important Extra Questions Set – 3

What is meant by the sublimation?

The process of changing of solid directly into gases state without changing into liquid, state or vice versa is known as sublimation.

Is there is any similarity in material?

Yes all material possess mass and occupy space.

When 50g of sugar is dissolved in 100ml of water there is no increase in volume. What characteristic of matter is illustrated by this observation?

This observation indicates that particles of water have space between them into which sugar particles fit.

What happens when an inflated air balloon is pricked with a pain? Name the property of the gaseous state exhibited by this observation.

The balloon burst and diffusion takes place.

Name the process which occur when a drop of Dettol is added to water.

When Dettol is added to water, diffusion take place.

Properties of Gas

    1. They do not have fixed shape and volume.
    2. They flow in all directions.
    3. They have high compressibility.
    4. It’s particle are more loosely packed than liquid.



Class 9 Science Chapter 1 Important Extra Questions Set – 4

To which physical states of matter do the following statements apply? (i) Incompressible, no fixed shape (ii) Compressible, no definite volume.

(i) Liquid
(ii) Gas

Name the state of matter in which: (i) Layers of particle can slip and slide over one another easily. (ii) Particles just move around randomly because of very weak force of attraction.

(i) Liquid state
(ii) Gaseous state

Define density and give its SI unit.

Density of a substance is defined as the mass per unit volume. Its SI unit kgm^-3.

In which of the following the particle have highest forces of attraction? Water, NaCl, ice or wax.

NaCl has particles with the highest forces of attraction.

When a crystals of potassium permanent is placed in a beaker containing water its purple colour spreads throughout the water. What do you conclude from this observation about the nature of potassium permanganate and water?

When we place few crystals of potassium permanganate in a beaker containing water we get two distinct layers colourless water at the top and pink colour at the bottom. After few minutes, pink colour spreads and whole solution turns pink due to diffusion. Since potassium permanganate is a solid substance, it does not possess so much space. Water molecules due to liquid states, collide with solid particles and intermixes due to sufficient space between molecules.

Classify the following into osmosis/diffusion

    1. Swelling up of a raisin on keeping in water.
    2. Spreading of virus on sneezing.
    3. Earthworm dying on coming in contact with common Salt.
    4. Shrinking of grapes kept in thick sugar syrup.
    5. Preserving pickles in salt.
    6. Spreading of smell of cake being baked throughout the house.
    7. Aquatic animals using oxygen dissolved in water during respiration.
Answers
    1. Osmosis.
    2. Diffusion.
    3. Osmosis.
    4. Osmosis.
    5. Osmosis.
    6. Diffusion.
    7. Diffusion.

Class 9 Science Chapter 1 Important Extra Questions Set – 5

Why do solids have a regular geometrical shape?

In solid the particles have highly ordered arrangement because the intermolecular forces between the particles are very strong. Therefore, solids have a regular geometrical shape.

Why are gases compressible but not liquids?

Gases are compressibility because the intermolecular space is very large in areas, whereas liquids are not compressibility because in liquids the intermolecular space is less.

Can a rubber band change its shape on stretching? Is it a solid?

Yes, rubber band change shape under force and regains the same shape when the force is removed. It breaks on applying excessive force. Yes it is a solid.

Why steam at 1000 C is better for heating purposes than water at 1000C?

Steam at 1000 C s better for heating purposes than water at 1000C because the energy of 1 kg of steam at 1000C is 22.6 × 105 joule which is more than that of 1kg of water at the same temperature.

Give two ways in which melting points and boiling points can be useful.

(a) To check whether the substance is pure or not.
(b) To identify the characteristic the substance.

Explain how the rate of evaporation of a liquid is affected

    1. Increases in temperature of the liquid.
    2. Decreases in exposed surface area.
    3. Increases in moisture in the surrounding air.
    4. Increases in wind speed.



Answers
    1. Rate of evaporation increases with rise in temperature.
    2.  Evaporation is less when exposed surface area decreases.
    3. Less evaporation if moisture content is high in air.
    4. Rate of evaporation increases if wind speed increases.

Class 9 Science Chapter 1 Important Extra Questions Set – 6

Alka was making tea in a kettle. Suddenly she felt intense heat from the puff of steam gushing out of the spout of the kettle. She wondered whether the temperature of the steam was higher than that of the water boiling in the kettle. Comment.

The temperature of both boiling water and steam 1000C but steam has more energy because latent heat of vaporisation.

Why does the temperature of substance remain constant during its melting point or boiling point?

The temperature of a substance remains constant at its melting and boiling points until all the substance melts or boils because, the heat supplied is continuously used up in changing the state of substance by overcoming the forces of attraction between the particles. This heat energy absorbed without showing any rise in temperature is given the name latent heat of fusion/latent heat of vapourisation.

What do you understand by the term latent? How much is the latent heat of fusion of ice?

The amount of heat that is required to change 1kg of solid into liquid at atmospheric pressure without any change in temperature at its melting point, is known as latent heat of fusion. The latent heat of fusion of ice in SI unit is 3.35 × 10^5 J/kg.

Which gas is called dry ice? Why?

Solid CO2 is known as dry ice. This is because is directly gets converted into gaseous state without passing through liquid state on decreasing the pressure to 1 atmosphere.

Why do the doctors advise to put strips of wet cloth on the forehead of a person having high fever?

When a person has fever his body temperature becomes more than the normal body temperature. If we put strips of wet cloth on the forehead of a person suffering from high fever, the water evaporates taking heat from the body. Thus moist strips will lower his body temperature.

Difference between Evaporation and Boiling

EvaporationBoiling
1. Evaporation takes place at all temperatures.1. Boiling takes place only at the boiling point of the liquid.
2. Temperature changes during evaporation.2. The temperature does not change during boiling.
3. It is a very slow process.3. It is a fast process.
4. Evaporation takes place only at the surface of the liquid.4. Boiling takes place in the entire body of the liquid.

Class 9 Science Chapter 1 Important Extra Questions Set – 7

Why do wet clothes dry quickly in the sun than in the shade?

The temperature in the sunny area is higher than in the shade and evaporation take place at a faster rate at high temperature. Hence wet clothes dry quickly in the sun.

Why do trees acquire more leaves during summer?

During summer the temperature is generally very high. In order to keep cool a tree must transpire (transpiration is a phenomena of evaporation of water from the leaves) more to keep itself cool. More transpiration requires more leaves. Hence a tree acquires more leaves during summer.

Why do we feel comfortable under a fan when we are perspiring?

The sweat is readily evaporated from the body by the air from the fan. As a result, we feel comfortable under a fan.

Why do people sprinkle water on the roof after a hot sunny day?

Water sprinkled on the roof evaporates by taking the large latent heat of vaporisation from the ground. This makes the place cool and comfortable.

It is not summer day, Priyanshi and Ali are wearing cotton and nylon clothes receptively. Who do you think would be more comfortable and Why?

Priyanshi would be more comfortable because cotton is a good absorber than nylon. It absorbs sweat from the body and provides large surface area for evaporation which causes cooling effect. As a result, body feels cool and comfortable.

An activity to show that the rate of diffusion of liquids decreases with increase in density of the liquid

    • Take two beaker filled with water.
    • Put a drop of blue ink slowly along the sides of the first beaker and honey in the same way in another beaker.
    • Leave it undistributed.
    • We observe the honey diffuses slowly as compared to ink.
    • This experiment shows that lesser the density faster the rate of diffusion.




Class 9 Science Chapter 1 Important Extra Questions Set – 8

Substance A has high compressibility and can be easily liquefied. It can take up the shape of any container. Predicted the nature of the substance. Enlist four properties of this state of matter.

A is a gas. Properties of gases are as follows:
(i) They do not have fixed shape and fixed volume.
(ii) They have large inter-particle space.
(iii) They have least forces of attraction between the molecules.
(iv) They are highly compressibility.

Explain what happens to molecular motion and energy 1Kg of water at 273K when it is changed into ice at same temperature. How is the latent heat of fusion related to the energy exchange that take place during this change of state?

(i) Molecular motion decreases as water gets converted into ice.
(ii) Latent heat of solidification is given off.
Latent heat of solidification is equal to latent heat of fusion.

You want to wear your favourite shirt to a party but the problem is that it is still wet after a wash. What steps would you take to dry it faster?

Conditions that can increases the rate of evaporation of water are:
(a) An increases in the surface area by spreading the shirt.
(b) An increases in the temperature by putting the shirt under the sun.
(c) Increases in the wind speed by spreading it under the fan.

Describe the continuous motion of particle of matter with the help of an activity.

(a) To demonstrate motion of particles in air:
(i) Place few lighted incense sticks in a corner of a room.
(ii) Move about the room and smell the fragrance of the incense sticks.
The fragrance produce produced due to burning of incense sticks is due to movement of vapours produce rapidly in all direction.
(b) To demonstrate motion of particle of solid matter:
(i) Drop a crystal of copper sulphate or potassium permanganate into a glass of hot water.
(ii) Do not stir the solution and allow the crystals to settle at the bottom.
(iii) The colour of the solid is seen spreading slowly. This is because the solid particles diffuse in the water.

Discuss the various factors which affect the rate of evaporation. Latent heat of evaporation of two liquids A and B is 100J/kg and 150J/kg respectively. Which one can produce more cooling effect and why?

Factors affecting the rate of evaporation:
(a) Surface area: The rate of evaporation increases with increase in surface area.
(b) Temperature: The rate of evaporation increases with increases in temperature.
(c) Humidity: The rate of evaporation decreases with increases in humidity.
(d) Wind Speed: The rate of evaporation increases with increases in wind speed.
(e) Nature of the liquid: The volatile compounds evaporate faster than less volatile compounds.
B will produce more cooling effect because it will absorb more heat from the surrounding for evaporation.

Determination of Boiling Point of Water
    • In a beaker take some water and insert a thermometer in it with the help of a clamp.
    • Put the beaker on a tripod stand and heat the apparatus with the help of kerosene burner slowly.
    • Observe what happen to water.
    • You will observe a steady stream of bubbles. This temperature is the boiling point of water.

Class 9 Science Chapter 1 Important Extra Questions Set – 9

Why is the smell of hot sizzling food reaches us server meter away but to get the smell from cold food you have to go close?

The particles of hot sizzling food get temperature and their kinetic energy increases so they move fast and mix up in the air and the smell reaches us while the temperature of particles of cold food is low so the particles of cold food is low so the particles do not move fast and they do not mix up in the air and reaches soon.

Why does Evaporation cause cooling?

Evaporation produces cooling aa the particles at the surface of the liquid grain energy from the surroundings and change into vapour thereby producing a cooling effect.

Rate of evaporation of an aqueous solution decreases with increases in humidity. Why?

Air around us cannot hold more than a definite amount of water vapour at a given temperature which is known as humidity. So if the air is already rich in water vapour, it will not take up more water therefore rate of evaporation of water will decrease.

Spongy though compressibility is a solid. Why?

A sponge has minutes’ holes in which air is trapped. Also the material is not rigid. When we press it the air is expelled out and we are able to compress it. But it is solid because it has definite shape and volume and does not change its shape unless compress.

Ice is solid at O degree while water is liquid at room temperature. Why?

Ice is solid at O degree Celcious because it has a definite volume and definite shape due to strong intermolecular force shape due to weak intermolecular force of attraction.

Determination of malting point of ice
    • Take crushed ice in a beaker and insert a thermometer in the beaker by hanging it from the clamp of the stand in such a way that the bulb of the thermometer is completely inside the ice.
    • Wait for some time and keep recording the temperature after small intervals of time.
    • Note down the temperature when ice just starts melting.
    • Let the bulb of the thermometer remain in mixture of ice and water for some more time and keep recording the temperature. This temperature is the melting point of ice.



Feedback and Suggestions

In Class 9 Science Chapter 1 Important Extra Questions, we have included almost all good questions from NCERT Books for Class 9 Science issued for academic session 2020-2021. More questions may be added as per the suggestions received by the users. If you have any suggestion related to these questions, please inform us to improve the data set of the questions. Your feedback and suggestions always make Tiwari Academy website more user friendly.