test

Chapter@1@Matter@in@Our@Surroundings@Intext@Questions@On@Page@3@Question@1:Which@of@the@following@are@matters?@Chair,@air,@love,@smell,@hate,@almonds,@thought,@cold,@cold-drink,@smell@of@perfume.@Solution:@Any@things@which@have@some@weight@and@occupy@space@will@come@under@category@of@matter.@Chair,@air,@smell,@almonds,@cold-drink@and@smell@of@perfume:@Matter@Question@2:Give@reasons@for@the@following@observation@The@smell@of@hot@sizzling@food@reaches@you@several@meters@away,@but@to@get@the@smell@from@cold@food@you@have@to@go@close.@Solution:@Evaporation@is@directly@proportional@to@temperature,@means@hot@food@evaporates@easily.Diffusion@of@hot@food@vapor@with@air@becomes@very@fast@and@can@reach@to@a@distant@place@within@a@very@short@time.@Question@3:A@diver@is@able@to@cut@through@water@in@a@swimming@pool.@Which@property@of@matter@does@this@observation@show?@Solution:@The@phenomena@of@cutting@the@water@by@the@diver@show@that@matter@has@space@between@its@particles.@Question@4:What@are@the@characteristics@of@the@particles@of@matter?@Solution:@Characteristics@of@particles@of@matter@are@given@below:@1.@Particles@of@matter@have@space@between@them.@2.@Particles@of@matter@are@continuously@moving.@3.@Particles@of@matter@have@an@attraction@force@between@them.@4.@Particles@of@matter@are@very@small@in@size.@On@Page@6@Question@1:The@mass@per@unit@volume@of@a@substance@is@called@density.@(Density@=@mass/volume).@Arrange@the@following@in@order@of@increasing@density–@Air,@exhaust@from@chimneys,@honey,@water,@chalk,@cotton@and@iron.@Solution:We@can@solve@this@question@by@keeping@this@concept@in@mind.@The@correct@order@of@density@for@gas,@liquid@and@solid@are:@Gas@<@Liquid@<@Solid.@Thus,@Air,@exhaust@from@chimneys@water,@honey,@cotton@,@chalk@,iron@Gas@Liquid@Solid@------------------------------------------------------------------------------------------->@Increasing@order@of@Density@Question@2:@(a)@Tabulate@the@differences@in@the@characteristics@of@states@of@matter.@(b)@Comment@upon@the@following:@Rigidity,@compressibility,@fluidity,@filling@a@gas@container,@shape,@kinetic@energy@and@density.@Solution:@(a)Solid@:@Solids@have@a@definite@volume.@Solids@do@not@tend@to@flow.@Solids@are@rigid.@Generally@solids@have@a@definite@shape@with@very@few@exceptions@like@sponge,@rubber@band@etc.@Solids@are@generally@incompressible@with@very@few@exceptions@like@sponge,@rubber@band@etc.@Liquid@:@Liquids@also@have@a@definite@volume.@Liquids@tend@to@flow.@Liquids@are@not@rigid.@Liquids@do@not@have@a@definite@shape.@They@take@the@shape@of@the@container.@Liquids@are@almost@incompressible.@Gases@:@Gases@do@not@have@a@definite@volume.@Their@volume@varies@with@the@container@in@which@they@are@stored@or@kept.@Gases@also@tend@to@flow@Gases@are@not@rigid.@Gases@do@not@have@a@definite@shape@Gases@are@compressible.@(b)@Rigidity:Property@by@which@an@object@retains@its@shape@and@size@is@called@as@rigidity.@Solids@are@rigid@whereas@liquids@and@gases@are@not.@Compressibility:@Compressibility@is@the@property;@due@to@which@a@substance@can@be@compressed,@means@its@volume@can@be@decreased.@Gases@are@compressible@whereas@solids@and@liquids@are@not.@Fluidity:@Flowing@tendency@of@a@substance@called@fluidity.@Gases@and@liquids@are@fluids,@solids@are@not.@Filling@a@gas@container:@a@large@volume@of@gas@can@be@filled@in@a@gas@container@by@compressing@it@under@very@high@pressure.@The@property@of@compressibility@(of@gases)@ivey@sue@full@in@this@case@Shape:The@property@of@having@a@definite@geometry@is@called@shape@of@a@particular@substance.@Solids@have@a@definite@shape@whereas@gases@and@liquids@do@not@have.@Kinetic@energy:@The@energy@possessed@by@a@moving@object@or@by@the@moving@molecules@of@called@kinetic@energy.@On@increasing@the@temperature,@kinetic@energy@of@a@substance@(or@its@molecules)@also@increases.@Molecules@of@gases@posses@highest@kinetic@energy.@Density@:@The@mass@per@unit@volume@of@a@substance@is@called@density.@Mass@Density@=@----------@Volume@Question@3:Give@reasons:@(a)@A@gas@fills@completely@the@vessel@in@which@it@is@kept.@(b)@A@gas@exerts@pressure@on@the@walls@of@the@container.@(c)@A@wooden@table@should@be@called@a@solid.@(d)@We@can@easily@move@our@hand@in@air@but@to@do@the@same@through@a@solid@block@of@wood@we@need@a@karate@expert.@Solution:@(a)@Force@of@attraction@between@the@molecules@of@gases@is@negligible.@So,@molecules@of@gases@occupy@the@maximum@space@available@to@them.@High@kinetic@energy@possessed@by@their@molecules@also@helps@for@the@same.@(b)The@motion@of@particles@is@random@and@having@very@high@speed@in@the@gaseous@state.Due@to@this@random@movement,@the@particles@hit@each@other@and@also@the@walls@of@the@container.@The@pressure@exerted@by@the@gas@is@due@to@this@force@exerted@by@these@particles@per@unit@area@on@the@walls@of@the@container.@(c)@There@is@a@strong@force@of@attraction@between@the@molecules@of@wood@and@the@intermolecular@space@is@the@least.@So,@a@wooden@table@has@a@definite@shape@and@volume@and@it@should@be@called@a@solid.@(d)@Air@molecules@are@very-very@far@from@each@other@due@to@negligible@force@of@attraction@working@between@them.@So,@our@hand@gets@sufficient@space@to@move@in@air@and@we@also@displace@some@air@molecules@by@applying@force.@But@a@solid@block@of@wood@has@closely@packed@molecules@so@there@is@no@question@of@the@movement@of@hand@through@it,@in@absence@of@suitable@force@in@proper@direction.@Question@4:Liquids@generally@have@lower@density@as@compared@to@solids.@But@you@must@have@observed@that@ice@floats@on@water.@Find@out@why?@Solution:Liquids@have@lower@density@than@that@of@solids.@Water@is@also@a@liquid@so@it@should@also@have@less@density@than@that@of@solid@that@is@ice.@But@the@case@is@not@so@and@the@reason@for@the@same@is@the@cage-like@structure@of@ice.@i.e.,@presence@of@vacant@spaces@between@water@(H2O)@molecules@when@they@linked@in@ice.@The@number@of@these@spaces@is@comparatively@less@in@water.@Being@more@porous@than@water,@ice@is@lighter@than@water@and@floats@over@the@surface@of@water.@On@Page@9@Question@1:Convert@the@following@temperature@to@Celsius@scale@(a)@300@K@(b)@573@K@Solution:@By@the@use@of@given@formula,@we@can@convert@the@Kelvin@temperature@to@Celsius.@T@K@–273@=@t°C@(a)@300K–273@=@27°C@(b)@573K–273@=@300°C@Question@2:What@is@the@physical@state@of@water@at@(a)@250°C@(b)@100°C?@Solution:@As@the@boiling@point@of@water@is@100°C@so@(a)@at@250°C,@the@state@of@water@will@be@steam@or@water@vapour,@i.e.,@gaseous@state.@(b)@at@100°C,@there@will@be@a@transition@of@liquid@state@into@the@gaseous@state.@So,@at@this@temperature,@the@state@is/may@be@liquid@as@well@as@gaseous.@Question@3:For@any@substance,@why@does@the@temperature@remain@constant@during@the@change@of@state?@Solution:During@the@change@of@state@of@a@substance,@the@temperature@remains@constant.@This@can@be@understood@with@the@help@of@an@example.@When@a@solid@is@heated@to@its@melting@point,@the@temperature@first@rises@and@becomes@constant@when@reaches@its@melting@point.@Now,@on@further@heating,@the@heat@energy@provided@to@the@substance@helps@to@break@the@attraction@force@between@the@solid@molecules.@This@heat@is@called@latent@heat.@That@is@why,@the@temperature@does@not@rise.@Question@4:Suggest@a@method@to@liquefy@atmospheric@gases.@Solution:By@applying@pressure@and@reducing@the@temperature,@atmospheric@gases@can@be@liquefied@On@Page@10@Question@1:Why@does@a@desert@cooler@cool@better@on@a@hot@dry@day?@Solution:A@desert@cooler@functions@on@the@basis@of@evaporation.@The@rate@of@evaporation@increases@with@increase@in@temperature@and@decrease@in@humidity.@As@evaporation@increases@when@the@day@is@hot@and@dry.@So,@the@desert@cooler@functions@to@a@better@extent.@Question@2:How@does@the@water@kept@in@an@earthen@pot@(matka)@become@cool@during@summer?@Solution:@Large@number@of@tiny@pores@is@present@on@the@surface@of@the@earthen@pot@(matka).@The@water@stored@in@the@earthen@pot@(matka)@evaporates@faster@through@these@pores@due@to@the@increased@exposed@surface@area.@As@the'@process@of@evaporation@causes@cooling,@the@stored@water@inside@the@earthen@pot@(matka)@becomes@cool.@Question@3:Why@does@our@palm@feel@cold@when@we@put@some@acetone@or@petrol@or@perfume@on@it?@Solution:Acetone,@petrol,@perfume@etc.,@being@volatile,@evaporate@very@fast@when@exposed@to@larger@surfaces.@During@the@process@they@absorb@the@required@latent@heat@of@vaporization@from@the@palm@(if@kept@on@palm).@So,@the@process@causes@Cooling@and@the@palm@feels@cool.@Question@4:Why@are@we@able@to@sip@hot@tea@or@milk@faster@from@a@saucer@rather@than@a@cup?@Solution:@A@liquid@has@large@surface@area@in@a@saucer@than@in@a@cup.@Thus,@it@evaporates@faster@and@cools@faster@in@a@saucer@than@in@a@cup.@For@this@reason@we@able@to@sip@hot@tea@or@milk@faster@from@a@saucer@rather@than@a@cup.@Question@5:What@type@of@clothes@should@we@wear@in@summer?@Solution:We@should@wear@light@colored@cotton@clothes@in@summer@because@1.@Cotton@is@a@good@absorber@of@water/sweat.@It@provides@more@surface@area@for@the@sweat@to@evaporate.@2.@Light@colours@absorb@less@heat.@So,@wearing@light@coloured@cotton@clothes@helps@us@feeling@cool@and@comfortable.@Exercises@Question@1:Convert@the@following@temperatures@to@the@Celsius@scale.@(a)@293@K@(b)@470@K@Solution:@In@order@to@covert@temperature@from@Kelvin@to@Celsius@scale,@we@have@to@subtract@273@from@the@given@value@because@K@-@273@=@°@C@(a)@293@K@-@273@=@20°C@(b)@470K@-@273@=@197°C@Question@2:Convert@the@following@temperatures@to@the@kelvin@scale.@(a)@25°C@(b)@373°C@Solution:@To@convert@temperature@from@Celsius@to@Kelvin@scale,@add@273@to@the@given@values@because@°@C@+@273@=@K@(a)@25°C@+@273@=@298@K@(b)@373°C@+@273@=@646@K@Question@3:Give@reason@for@the@following@observations.@(a)@Naphthalene@balls@disappear@with@time@without@leaving@any@solid.@(b)@We@can@get@the@smell@of@perfume@sitting@several@meters@away.@Solution:@(a)@Naphthalene@is@a@substance@which@directly@changes@from@solid@to@gas@on@heating@by@the@process@of@sublimation.@So,@the@naphthalene@balls@disappear@with@time@as@they@sublime@due@to@heat@of@surroundings.@(b)@The@smell@(aroma)@of@perfume@reaches@several@meters@away@due@to@the@fast@diffusion@of@the@gaseous@perfume@particles@through@the@air.@Question@4:Arrange@the@following@substances@in@increasing@order@of@forces@of@attraction@between@the@particles-water,@sugar,@oxygen.@Solution:The@forces@of@attraction@are@strongest@in@solids@and@weakest@(or@negligible)@in@case@of@gases.@Sugar@is@a@solid,@water@is@in@liquid@form@and@oxygen@is@a@gas@so,@the@order@of@forces@of@attraction@is@oxygen@<@water@<@sugar.@Question@5:What@is@the@physical@state@of@water@at@(a)@25°C@(b)@0°C@(c)@100°C?@Solution:At@zero@°C@temperature@water@(liquid)@get@starts@to@convert@into@its@solid@form@(ice)@and@at@100°C@temperature@water@(liquid)@starts@to@change@into@water@vapours@.Between@0°@to@100°C@it@remains@in@liquid@state.@Thus,@(a)@Liquid@state@(b)@Solid@or/and@liquid@state@(Transition@state)@(c)@Liquid@or/and@gaseous@state@(Transition@state)@Question@6:Give@two@reasons@to@justify@(a)@Water@at@room@temperature@is@a@liquid.@(b)@An@iron@almirah@is@a@solid@at@room@temperature.@Solution:@(a)@Water@is@a@liquid@at@room@temperature@because@It@has@a@tendency@to@flow.@It@takes@the@shape@of@the@container@in@which@it@is@filled,@but@its@volume@remains@the@same.@(b)@An@iron@almirah@is@a@solid@at@room@temperature@because@Its@shape@and@volume@are@definite.@It@is@hard@and@rigid.@Its@density@is@high.@Question@7:Why@is@ice@at@273@K@more@effective@in@cooling@than@water@at@the@same@temperature?@Solution:Ice@at@273K@has@less@energy@than@water@(although@both@at@the@same@temperature).@Water@is@having@additional@latent@heat@of@fusion,@hence@at@273@K@ice@is@more@effective@cooling@than@water@Question@8:What@produces@more@severe@burns,@boiling@water@or@steam?@Solution:Steam@causes@more@severe@burns@than@boiling@water.@The@reason@is@that@it@releases@the@extra@amount@of@heat@(latent@heat)@which@it@has@already@taken@during@vaporization@Question@9:Name@A,@B,@C,@D,@E@and@F@in@the@following@diagram@showing@change@in@its@state.@Solution@:@A@=@Melting@or@fusion,@where@solid@changes@into@liquid.@B@=@Evaporation@or@vaporization,@where@liquid@changes@into@gas.@C@=@Condensation@or@liquification@where@gas@changes@into@liquid.@D@=@Freezing@or@solidification,@where@liquid@changes@into@solid.@E@=@Sublimation,@where@solid@directly@changes@into@gas@without@coming@in@liquid@state.@F@=@Sublimation,@where@gas@changes@into@solid@without@coming@to@liquid@state.