4 MORE ABOUT SOLIDS, LIQUIDS AND GASEStestlabz.com/ModelPapers/5_15_47_387.pdf · 2020. 9. 22. ·...

1Class-VIII Physics Question Bank

4 MORE ABOUT SOLIDS, LIQUIDS AND GASES

I. Tick (✔✔✔✔✔) the most appropriate answer.1. The fluid used in aneroid barometer is:

(a) water (b) mercury (c) air (d) none of these2. The normal atmospheric pressure is:

(a) 70 cm of mercury (b) 76 cm of mercury(c) 67 cm of mercury (d) 80 cm of mercury

3. The intermolecular spaces in case of liquids is:(a) less than solids (b) more than gases(c) more than solids (d) more than solids and gases

4. The kinetic energy of molecules of a gas increases with:(a) fall in temperature (b) rise in temperature(c) decrease in pressure (d) increase in pressure

5. The pressure exerted at any point on an enclosed liquid is transmitted:(a) only towards the sides of vessel(b) only towards the base of vessel(c) in all directions of the vessel(d) none of these

6. When a body is fully immersed in liquid, the apparent loss in theweight of the body is equal to:(a) volume of liquid displaced by body(b) density of the liquid(c) weight of liquid displaced by body(d) none of these

7. When an ink fountain pen leaks on high altitude:(a) pressure of atmosphere is more than pressure inside the pen(b) pressure of atmosphere is less than pressure inside the pen(c) the density of ink on high altitude decreases(d) none of these

8. When the weight of a given body is less than weight of fluid displacedby it, then the body:


(a) sinks(b) floats(c) just keeps in line with the surface of fluid(d) none of these

9. Buoyant force exerted by a fluid on a given body is:(a) equal to the volume of body(b) equal to the weight of body(c) equal to the volume of fluid displaced by body(b) equal to the weight of fluid displaced by the body

10. Heat is transmitted in liquids by:(a) conduction(b) convection(c) both conduction and convection(d) none of these

11. A device to measure the liquid pressure is:(a) barometer (b) thermometer (c) manometer (d) lactometer

12. The liquid used in a simple barometer is:(a) water (b) alcohol (c) mercury (d) kerosene

13. Liquid pressure with increasing depth:(a) decreases (b) remains the same(c) increases (d) none of these

14. The pressure exerted at any point on an enclosed liquid is transmitted:(a) only at the bottom (b) only on the sides(c) in all directions (d) none of these

15. Buoyant force experienced by a body partly or wholly immersed ina fluid is called:(a) upward force (b) horizontal force(c) downward force (d) none of these

16. Buoyant force exerted by a fluid on a body is equal to the(a) weight of the body:(b) apparent loss of weight of the body(c) mass of the body(d) none of these


17. If the weight of the body is more than the weight of fluid displacedby it, then the body:(a) float (b) first floats and then sinks(c) sinks (d) none of these

Ans. 1. (d) 2. (b) 3. (c) 4. (b) 5. (c) 6. (c)7. (b) 8. (b) 9. (d) 10. (b) 11. (c) 12. (c)

13. (c) 14. (c) 15. (a) 16. (b) 17. (c)II. Fill in the blanks.

1. Kinetic energy of the molecules ___________ with the increase intemperature.

2. With the increase in _____________ the intermolecular forcesdecrease.

3. The Phenomenon due to which exposed surface of a liquid behaveslike stretched membrane is called _____________.

4. Mercury forms spherical droplets, because it has no force of_____________ with glass surface.

5. The meniscus formed by water in a test tube is of_____________shape.

6. With the increase in the volume of an enclosed gas, its pressure_____________.

7. Convection in liquids takes place due to _____________ of itsmolecules.

8. The pressure in liquids is independent of _____________ of vessel.9. The atmospheric pressure at sea level is 100,000 _____________.

10. When a solid floats in a liquid, then the weight of whole __________is equal to the weight of liquid displaced by its immersed part.

11. All matter is made up of _____________.12. Molecules of the same type _____________ each other.13. A liquid droplet is in the shape of a _____________.14. When a substance is heated, the kinetic energy of the molecules

_____________.15. When a gas is allowed to expand at a constant temperature its

pressure ____________.


16. Liquid pressure does not depend upon _____________.17. For an object floating in water, its apparent loss of weight will be

_____________ buoyant force.18. The atmospheric pressure at sea level is ____________ mm – Hg.19. Liquid pressure remains the _____________ in all directions at a

given depth.20. Pressure exerted by the liquids on the sides of the containing vessel

is called _____________.21. At high altitudes, the atmospheric pressure _____________.22. The force of attraction between the molecules of different substances

is called _____________ force.23. The force of attraction between molecules of the same substance is

called _____________.24. If the weight of a body is equal to the buoyant force, it will _________

in the fluid.25. A submarine can sink or rise up by filling or emptying its _________.26. A brick feels _____________ in water than in air.27. An iceberg is considered dangerous because it floats with only

_____________ of its volume above water.28. Buoyant force is equal to the loss of _____________ of the body

when it is immersed in a fluid.29. The upward force exerted by a liquid on an object immersed in it, is

called _____________.30. Mass per unit _____________ is called the _____________.31. Larger the volume of a body immersed in a liquid the ____________

is the upthrust.32. When the weight of a body is less than the weight of the liquid

displaced by it, the body will_____________.33. When the weight of a body is greater than the weight of the liquid

displaced by it, the body will_____________.Ans. 1. increases 2. intermolecular spaces 3. surface tension

4. adhesion 5. concave 6. decreases7. motion 8. area of cross-section 9. Pascals


10. soild 11. molecules 12. attract13. sphere 14. increases 15. decreases16. shape of the vessel 17. equal to 18. 76019. same 20. lateral pressure 21. decreases22. adhesion 23. cohesion 24. float25. ballast tanks 26. lighter 27. a part28. weight 29. upthrust 30. volume, density31. greater 32. float 33. sink

III. The statements given below are incorrect, write the correctstatements.

1. When a solid floats in a liquid then the density of solid is alwaysmore than the density of liquid.

Ans. When a solid floats in a liquid then the density of solid is always lessthan the density of liquid.

2. When the tube of a barometer is tilted, it records a differentatmospheric pressure.

Ans. When the tube of a barometer is tilted, it records the same atmosphericpressure.

3. Molecule is the smallest unit of matter, which may or may not havean independent existence, but always takes part in a chemical reaction.

Ans. An atom is the smallest unit of matter, which may or may not havean independent existence, but always takes part in a chemical reaction.

4. Meniscus is formed in the liquids due to the force of gravity.Ans. Meniscus is formed in the liquids due to the strong force of cohesion.

5. Buoyant force of a liquid increases with the decrease in the densityof liquid.

Ans. Buoyant force of a liquid increases with the increase in the densityof liquid.

6. The pressure of an enclosed gas increases with the increase in thevolume of gas.

Ans. The pressure of an enclosed gas decreases with the increases in thevolume of gas.

7. Liquids exert same pressure in all directions at different depths.


Ans. Liquids exert same pressure in all directions at same depths.8. Moisture in mercury increases the barometric height.

Ans. Moisture in mercury decreases the barometric height.9. When a solid is completely immersed in a fluid, then the apparent

loss of weight of solid is more than the weight of fluid displaced.Ans. When a solid is completely immersed in a fluid, then the apparent

loss of weight of solid is equal to volume of fluid displaced.10. Solids can be compressed because the molecules are arranged close

together.Ans. Solids cannot be compressed because the molecules are arranged

close together.11. The relation between the upthrust and the weight of the liquid

displaced by a submerged object was first discovered by a Greekmathematician and scientist named Aristotle.

Ans. The relation between the upthrust and the weight of the liquiddisplaced by a submerged object was first discovered by a Greekphilospher and scientist named Archimedes’.

12. Objects appear heavier when kept immersed in a fluid.Ans. Objects appear lighter when kept immersed in a fluid.

13. Buoyant force is experienced only when objects are immersed inliquids and not in gases.

Ans. Buoyant force is experienced when objects are immersed in liquidsand gases both.

14. Buoyant force acts in all directions.Ans. Buoyant force acts in upward direction.

15. The barometer reading changes for different positions at the samedepth.

Ans. The barometer reading is same for different positions at the samedepth.

16. Atmospheric pressure increases as we move from sea level to higheraltitude.

Ans. Atmospheric pressure decreases as we move from sea level to higheraltitude.


17. Conduction takes place due to molecular movement.Ans. Conduction takes place due to molecular vibration.

18. With the decrease in intermolecular space, the intermolecular forcesdecrease.

Ans. With the decrease in intermolecular space, the intermolecular forcesincrease.

19. Aneroid barometer used pure mercury.Ans. Aneroid barometer uses no liquid.

20. With the decrease in the volume of gas its pressure decreases.Ans. With the decrease in the volume of gas its pressure increases.

IV. Name the following.1. The scientist who first proposed that molecules are constantly

moving.2. The force between the molecules of two different types of substances.3. The state of matter in which it is easily compressible.4. The curve surface of a liquid column.5. A mode of heat transference accompanied by the physical movement

of molecules.6. The upward force experienced by an object when immersed in a

fluid.7. The instrument used to measure atmospheric pressure.

Ans. 1. Robert Brown 2. Adhesive force 3. Gaseous4. Meniscus 5. Convection 6. Upthrust7. Barometer

V. Define these terms.1. Surface tension

Ans. Surface tension: The phenomenon due to which exposed (top)surface of a liquid contained in a vessel behaves like a stretchedmembrane is called surface tension.

2. CohesionAns. Cohesion: The force of attraction existing between the molecules

of the same type is reduce called the cohesion.


3. AdhesionAns. Adhesion: Adhesion is the force of attraction between the molecules

of different substances.4. Atmospheric pressure

Ans. Atmospheric pressure: The thrust on the unit area due to the columnof air on the earth’s surface is called atmospheric pressure.

5. ConductionAns. Conduction: The process of transfer of heat in solids, from one

particle to another without the actual movement of the particle iscalled conduction.

6. ConvectionAns. Convection: The mode of heat transference in liquids and gases,

taking place by the actual movement of molecules from one part toanother is called convection.

7. MeniscusAns. Meniscus: The formation of curved surface by the exposed surface

of the liquid contained in a narrow vessel is called meniscus.VI. Match the following.

1. Intermolecular force (a) force of attraction betweenmolecules of the substance

2. Cohesion (b) distribution of thrust exerted by aliquid due to its own weight

3. Adhesion (c) force of attraction betweenmolecules

4. Liquid pressure (d) force of attraction betweenmolecules of different substances

Ans. 1. (c), 2. (a), 3. (d), 4. (b)VII. Differentiate between the following.

1. Solids and liquids on the basis of arrangement of molecules.Ans. In solids, there is very less space between the molecules and they

are tightly packed. So they have a definite shape and definite volume.While in liquids intermolecular space is more than solid and they areless tightly packed. So they have a definite shape but no definite volume.


2. Conduction and convection.Ans. The mode of transmission of heat energy from one atom to another

atom, in the direction of lower temperature without the actualmovement of atoms from their mean position is called conduction.It takes place in solids.The phenomenon, due to which particles of a medium actually movetowards the source of heat energy, and then on absorbing heat energymove away from it, thereby making a space for other particles ofmedium to move towards the source of heat is called convection. Ittakes place in liquids and gases.

3. Liquid pressure and atmospheric pressure.Ans. All liquids apply pressure on the walls and bottom of their container.

The force applied by liquid per unit area is called liquid pressure.The force exerted by atmosphere per unit area on the surface ofearth is called atmospheric pressure.

VIII. Give reasons for the following.1. Mercury does not “wet” glass.

Ans. The cohesive forces between the molecules of mercury is greaterthan the adhesive forces between the molecules of mercury andglass. Thus mercury does not “wet” glass.

2. The sides of an empty can do not collapse inwards.Ans. The atmospheric pressure acts equally in all directions that is why

the sides of an empty can are not pushed in as the air pressureinside the can is the same as the air pressure outside.

3. You will be able to lift a heavy object quite easily inside water.Ans. According to Archimedes’ Principle, when a body is wholly or

partially immersed in a fluid, it experiences an upthrust equal to theweight of the fluid displaced by the body. Hence, the object feelsmuch lighter inside water than its actual weights. So we are able tolift a heavy object quite easily in water.

4. If a thermometer is broken, small drops of mercury will roll like littleballs.

Ans. If a thermometer is broken small drops of mercury roll like little


balls due to surface tension.5. A gas can be easily compressed.

Ans. The molecules of a gas are very far apart and they have very largeintermolecular spaces. So a gas can be easily compressed by applyingpressure.

6. Water has a tendency to form spherical droplets.Ans. Water has tendency to form spherical droplets due to surface tension

which is mainly caused due to unbalanced cohesive force actingnear the top surface of a liquid.

7. Hydrogen-filled balloons tend to float upwards.Ans. Hydrogen is lighter than air, so hydrogen filled balloons tend to float

upwards.8. Giant hot-air balloons rise up.

Ans. When air is heated, it gets lighter and tends to rise upward, so gianthot air balloons rise up.

9. A piece of iron floats in mercury but sinks in water.Ans. Density of mercury (13.6 g cm–3) is higher than that of water

(1 g cm–3), thus mercury exerts more upthrust on iron piece. So apiece of iron floats in mercury and sinks in water.

10. A balloon filled with helium gas rises up.Ans. Since, helium gas is lighter than air, so a balloon filled with helium

gas rises up.11. One find easier to swim in sea water as compared to pure swimming

pool water.Ans. Since density of sea water is more than pure swimming pool water.

So sea water exerts more upthrust on the body, and hence, one findeasier to swim in sea water as compared to pure swimming poolwater.

12. Only a tip of iceberg visible outside the water surface.Ans. As the density of ice is slightly less than sea water, therefore only a

tip of iceberg is visible outside the water surface.IX. Answer the following questions.

1. State three factors which determine pressure in liquids.


Ans. The three factors which determine pressure in liquids are:(a) Pressure in a liquid is directly proportional to its height (depth)(b) Pressure in a liquid is directly proportional to its density.(c) Pressure in a liquid is directly proportional to the acceleration

due to gravity.2. Describe an experiment to prove that lateral pressure in liquids is

directly proportional to the depth of liquid.Ans. Experiment to prove that lateral pressure

in liquids is directly proportional to thedepth of liquid:We take a metallic cylinder with a smallopening near the base tied with a smallrubber balloon. Now gradually pour waterinto the cylinder. We observe that with theincrease in the level of water, the balloonstarts bulging, i.e. more the depth of waterthe more is the lateral pressure.

3. Define the following terms: (a) element (b) atom (c) molecule.Ans. (a) Element: An element is defined as a substance, which cannot

be subdivided into two or more simple substances by anychemical means.

(b) Atom: An atom is defined as the smallest unit of an elementwhich may or may not have an independent existence, but alwaystakes part in a chemical reaction.

(c) Molecule: Molecule is defined as the smallest unit of matter,which has an independent existence and can retain completephysical and chemical properties of matter.

4. State five important points of kinetic theory of matter.Ans. The five important points of kinetic theory of matter are:

(i) Molecules are in a state of continuous motion, which does notstop over any length of time.

(ii) The kinetic energy of the molecules increases with the increasein temperature and vice versa.


(iii) The molecules always attract each other. The force of attractionbetween similar kind of molecules is called force of cohesionwhile the force of attraction between different kinds of moleculesis called force of adhesion.

(iv) The empty space between the molecules is called intermolecularspace.

(v) The intermolecular force of attraction increases if theintermolecular space between the molecules decreases and viceversa.

5. On the basis of kinetic theory of matter explain.(a) Why the solids have a definite volume and definite shape?(b) Why the liquids have a definite volume but no definite shape?(c) Why the gases have no definite volume and no definite shape?

Ans. (a) Intermolecular spaces between the molecules of a solid are verysmall, so the molecules attract one another with a strong forcewhich holds the molecules at one particular place. Because ofthe fixed position of the molecules, the solids have a definiteshape and definite volume.

(b) Intermolecular spaces between the molecules of a liquid arelarge, so the molecules attract each other with a lesser force.Due to this, the molecules do not stay at one place. Instead,they interchange their position and take the shape of thecontaining vessel. So liquids have a definite volume but nodefinite shape.

(c) In gases, the molecules are very much far apart, and moveindependently. So, the gases have no definite volume and nodefinite shape.

6. (a) What do you understand by the term surface tension?(b) Name the force responsible for surface tension.(c) Why does a small amount of mercury on placing over a glass

plate form a spherical ball?(d) Why does a small amount of water on placing over a glass

place form an oval shaped drop?


Ans. (a) The phenomenon due to which exposed (top) surface of a liquidcontained in a vessel behaves like a stretched membrane is calledsurface tension.

(b) The surface tension is mainly caused due to unbalanced cohesiveforce.

(c) The unbalanced cohesive force acting on the molecules of liquidat the surface tends to pull them towards the centre of the liquid.It reduces the surface area and cause droplets of mercury totake a spherical shape.

(d) When a small amount of water is poured on a glass plate, ittakes an oval shape. It is because the force of attraction betweenthe molecules of water i.e., the force of cohesion is far less thanthe force of adhesion between the molecules of water and theglass plate.

7. What do you understand by the term meniscus? Name the kind ofmeniscus formed (a) in case of water (b) in case of mercury.

Ans. The formation of curved surface by the exposed surface of a liquidcontained in a narrow vessel is called meniscus.(a) Concave meniscus is formed in case of water and (b) convexmeniscus is formed in case of mercury.

8. Liquids exert pressure. Explain on the basis of kinetic model.Ans. The molecules of a liquid in a closed vessel are not stationary but

move about randomly in all possible directions. In doing so, themolecules of liquid strike against the side of container, and hence,exert some force. This force exerted per unit area on the sides ofcontaining vessel is the cause of liquid pressure.

9. Gases exert pressure. Explain on the basis of kinetic model.Ans. The molecules of a gas in a closed vessel are not stationary but

move about randomly in all possible directions. In doing so, themolecules of a gas strike against the side of container and henceexert some specific force. This force exerted per unit area on thesides of containing vessel is the cause of gas pressure.

10. How does the pressure of an enclosed gas change with the decrease


in volume? Explain it on the basis of kinetic model of matter.Ans. With the decrease in volume of an enclosed gas, its pressure increases.

When the gas is compressed to half its volume, the number ofmolecules per unit volume of the gas becomes double. So the forceexerting against the side of container is also doubled. Therefore, thepressure of the enclosed gas is doubled.

11. Solids get heated by conduction. Explain conduction on the basisof kinetic model of matter.

Ans. When a solid is heated from one end, its atom gain heat energy dueto which their kinetic energy increases and hence they vibrate abouttheir mean positions with more amplitude. Thus these energetic atomsstrike against the neighbouring atoms and transfer a part of kineticenergy to them. Thus, the temperature of the conductor rises.

12. Fluids get heated by convection. Explain convection on the basis ofkinetic model of matter.

Ans. When a fluid is heated from the base of the container, then theparticles in that region absorb heat energy which increases kineticenergy of the molecules. Hence, they move more vigorously. Theseenergetic particles rise upward which results in fall in pressure. Toequalise the pressure, the particles of liquid from the colder regionssink down. This in turn gives rise to convection current.

13. How does liquid pressure, depends upon the following?(a) depth of liquid (b) density of liquid(c) acceleration due to gravity at a given place(d) area of cross-section of the containing vessel

Ans. (a) Liquid pressure is directly proportional to the depth of liquid.(b) Liquid pressure is directly proportional to its density.(c) Liquid pressure is directly proportional to the acceleration due

to gravity at a given place.(d) Liquid pressure is independent of the area of cross-section of

the containing vessel.14. Why are the walls of a hydroelectric dam made thick at the base of

dam?


Ans. The walls of the dam are made very thick at the base, so that theycan withstand lateral pressure which increases with increase in depthof liquid.

15. Why do the deep sea divers wear specially designed suits?Ans. Pressure of the liquid increases with increase in depth. As sea divers

go deep down into the sea, the liquid pressure exerted on themwould be so great that would even crushed. So deep sea diverswear a specially designed suits to withstand this pressure.

16. What do you understand by the term atmospheric pressure? Whatis its average value at sea level?

Ans. The force exerted by atmosphere per unit area on the surface ofearth is called atmospheric pressure. The average value ofatmospheric pressure at sea level is 76 cm of vertical height ofmercury.

17. The atmospheric pressure at sea level is 76 cm of mercury. What doyou understand by the statement.

Ans. The atmospheric pressure at sea level is 76 cm of mercury. It meansair exerts as much pressure at sea level as is exerted by 76 cm ofvertical height of mercury column.

18. Describe briefly the construction of simple barometer?Ans. A simple barometer is obtained by inverting a mercury filled tube

about 100 cm in length and closed at one end in a trough filled withmercury, taking care not to let in air by inverting the tube.

19. What do you understand by the term buoyancy and buoyant force?State two factors which determine the buoyant force exerted by a liquid.

Ans. Buoyancy: The phenomenon due to which a body experiences anupward force when partly or wholly immersed in a fluid is calledbuoyancy.Buoyant force: An upward force experienced by a body whenpartly or wholly immersed in a fluid is called buoyant force.Factors determining buoyant force:(i) Buoyant force is directly proportional to the volume of the fluid

displaced by solid.


(ii) Buoyant force is directly proportional to the density of fluiddisplaced by solid.

20. How does the atmospheric pressure decrease due to change inaltitude?

Ans. As we go up in the atmosphere, the atmospheric pressure decreases.At a height of 1 km above sea level, the height of mercury column inthe barometer falls to 73 cm. At a height of about 40 km above thesea level the air pressure is only about 1 cm of mercury.

21. (a) State Archimedes’ Principle.(b) Briefly describe, how will you verify Archimedes’ Principle.

Ans. (a) Archimedes’ Principle:- “When a body (solid) is partly or whollyimmersed in a fluid, it experiences an upward force which isequal to the weight of the fluid displaced by the immersed partof the body.”

(b) Verification of Archimedes’ Principle:(i) Take a glass stopper and tie it to a spring balance. Let its

weight be W1g.(ii) Take an overflow jar filled with beaker and place in a

clean beaker. Weigh the empty beaker. Let it be W3g.(iii) Now lower the stopper carefully in the overflow jar. Note

the weight of the stopper when it is completely immersed.Let it be W2g. As the stone is immersed into the overflowjar, it displaces water which is collected in the beaker. Letthe weight of beaker along with water displaced be W4g.

Weight of stopper in air = W1 gWeight of stopper when fully immersed in water = W2 g

Weight of empty beaker = W3 gWeight of beaker plus displaced water = W4 gApparent loss in weight of water = (W1– W2) g

Let us say a1 g.Weight of water displaced = (W4 – W3) g

Let us say a2 g.We will see that a1 = a2


i.e. (W1 – W2) = (W4 – W3)The apparent loss of weight of the stone or the buoyant force on itwill be found to be equal to the weight of the water displaced, thusverifying Archimedes’ Principle.

22. (a) State the law of floatation.(b) Why does ice float on the surface of water?

Ans. (a) Law of floatation: It states that when a body is floating in aliquid, then the weight of whole body acting vertically downwardis equal to the weight of the liquid displaced by the immersedpart of the body, acting vertically upward.

(b) Density of ice is around 0.91 g cm–3 at 0°C which is less than

density of fresh water 1 g cm–3. When ice is dropped in water,it experiences a greater buoyant force than its own weight andthus ice floats on the surface of water.

23. Why do ink pens start leaking on high altitude?Ans. On higher altitudes fountain pens start leaking because air inside the

pen is at higher pressure than air outside.24. Why is the hearing affected while coming down from hills?

Ans. There is less atmospheric pressure at the hills, so the hearing isaffected while coming down from hills.

25. State Pascal’s law?Ans. Pascal’s law,” It states that when pressure is applied to any part of

an enclosed liquid it is transmitted equally in all directions withundiminished force and acts at right angles to the surface of vessel.

26. A piece of iron sinks in water but large ships made of iron float onwater. Explain why?

Ans. According to law of floatation, those objects which are less densethan water will float in water and the objects whose density is greaterthan water will sink. The average density of ship is less than that ofwater whereas that of piece of iron more than that of water. Hence,larger ship floats and an iron piece sinks.

27. Why is mercury used in a barometer?Ans. Mercury is used in a barometer because


(a) density of mercury is very high and a short length of mercurycan counterbalance normal atmospheric pressure.

(b) it does not wet the sides of glass tube, and hence, helps inrecording true atmospheric pressure.

(c) it is easily seen in the glass tube.28. What are the defects of a simple mercury barometer?

Ans. A simple mercury barometer has following defects:(a) As the apparatus is all glass, therefore, there is chance of its

breakage.(b) The level of mercury in the glass trough increases or decreases

with the change in atmospheric pressure. Thus a permanentscale cannot be marked on the glass tube.

(c) It is neither compact, nor portable, thus it cannot be carried todifferent places.

29. When a solid substance is heated, what happens to its molecule?Ans. When a solid is heated, kinetic energy of its molecules increases

and hence they vibrate about their mean positions with more amplitudeand after some time, the solid begins to change into liquids.

30. Why are liquids and gases called fluids?Ans. Liquids and gases have the property to flow. Liquids flow from

upward to downward direction while gases flow in all directions.So, liquids and gases are called fluids.

Date post:	24-Aug-2021
Category:	Documents
Upload:	others
View:	2 times
Download:	0 times

4 MORE ABOUT SOLIDS, LIQUIDS AND GASEStestlabz.com/ModelPapers/5_15_47_387.pdf · 2020. 9. 22. ·...

Documents