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CBSE Board Exam Class 10 2019 : Science (Series 4)

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CBSE 10
Kendriya Vidyalaya (KV), Kamla Nehru Nagar, Ghaziabad
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SET-1 H$moS> Z . Series JMS/4 Code No. amob Z . 31/4/1 narjmWu H$moS >H$mo C ma-nwp VH$m Ho$ _wI-n >na Ad ` {bIo & Roll No. Candidates must write the Code on the title page of the answer-book. H $n`m Om M H$a b| {H$ Bg Z-n _o _w{ V n > 15 h & Z-n _| Xm{hZo hmW H$s Amoa {XE JE H$moS >Z ~a H$mo N>m C ma -nwp VH$m Ho$ _wI-n > na {bI| & H $n`m Om M H$a b| {H$ Bg Z-n _| >27 Z h & H $n`m Z H$m C ma {bIZm ew $ H$aZo go nhbo, Z H$m H $_m H$ Ad ` {bI| & Bg Z-n H$mo n T>Zo Ho$ {bE 15 {_ZQ >H$m g_` {X`m J`m h & Z-n H$m {dVaU nydm _| 10.15 ~Oo {H$`m OmEJm & 10.15 ~Oo go 10.30 ~Oo VH$ N>m Ho$db Z-n H$mo n T>|Jo Am a Bg Ad{Y Ho$ Xm amZ do C ma-nwp VH$m na H$moB C ma Zht {bI|Jo & Please check that this question paper contains 15 printed pages. Code number given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate. Please check that this question paper contains 27 questions. Please write down the Serial Number of the question before attempting it. 15 minute time has been allotted to read this question paper. The question paper will be distributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the students will read the question paper only and will not write any answer on the answer-book during this period. {dkmZ SCIENCE {ZYm [aV g_` : 3 K Q>o A{YH$V_ A H$ : 80 Time allowed : 3 hours 31/4/1 Maximum Marks : 80 1 P.T.O. gm_m ` {ZX}e : (i) Bg Z-n H$mo nm M ^mJm|, A, ~, g, X Am a | ~m Q>m J m h & AmnH$mo g^r ^mJm| Ho$ Zm| Ho$ C ma {bIZo h & (ii) g^r Z A{Zdm` h & (iii) ^mJ ~, g, X Am a Ho$ Zm| | Am V[aH$ M Z {X m J m h & (iv) ^mJ A Ho$ Z g `m 1 Am a 2 EH$-EH$ A H$ Ho$ Z h & BZHo$ C ma EH$ e X AWdm EH$ dm ` _| XoZo h & (v) ^mJ ~ Ho$ Z g m 3 go 5 Xmo-Xmo A H$m| Ho$ Z h & BZHo$ C ma bJ^J 30 e Xm| `oH$ | XoZo h & (vi) ^mJ g Ho$ Z g m 6 go 15 VrZ-VrZ A H$m| Ho$ Z h & BZHo$ C ma bJ^J 50 e Xm| `oH$ | XoZo h & (vii) ^mJ X Ho$ Z g m 16 go 21 nm M-nm M A H$m| Ho$ Z h & BZHo$ C ma bJ^J 70 e Xm| `oH$ | XoZo h & (viii) ^mJ Ho$ Z g m 22 go 27 moJm H$ H$m eb na AmYm[aV Xmo-Xmo A H$m| Ho$ Z h & BZHo$ g {j V C ma XoZo h & General Instructions : (i) The question paper comprises five Sections, A, B, C, D and E. You are to attempt All the sections. (ii) All questions are compulsory. (iii) Internal choice is given in Sections B, C, D and E. (iv) Questions number 1 and 2 in Section A are one-mark questions. They are to be answered in one word or in one sentence. (v) Questions number 3 to 5 in Section B are two-marks questions. These are to be answered in about 30 words each. (vi) Questions number 6 to 15 in Section C are three-marks questions. These are to be answered in about 50 words each. (vii) Questions number 16 to 21 in Section D are five-marks questions. These are to be answered in about 70 words each. (viii) Questions number 22 to 27 in Section E are based on practical skills. Each question is a two-marks question. These are to be answered in brief. ^mJ A 1. 2. SECTION A {VamoY H$s n[a^mfm Xr{OE Am a BgH$m S.I. m H$ {b{IE Define resistance. Give its S.I. unit. & Eogo {H$ ht Xmo V dm| H$m Zm {b{IE {OZH$m Cn moJ gm a gobm| Ho$ g {daMZ (~ZmZo) | {H$ m OmVm h & Name any two elements that are used in fabricating solar cells. 31/4/1 2 1 1 ^mJ ~ SECTION B 3. 2 H$me Ho$ namdV Z Ho$ {Z {b{IE AWdm {Zanoj AndV Zm H$ H$s n[a^mfm {b{IE Am a Bgo J{UVr $n | V H$s{OE & 2 State laws of reflection of light. OR Define absolute refractive index and express it mathematically. 4. 2 {H$gr N> S> Mw ~H$ Ho$ Mmam| Amoa Mw ~H$s jo aoImE It{ME & Draw magnetic field lines around a bar magnet. 5. m hmoVm h O~ {H$gr naIZbr | ^ao JwZJwZo mo{nb Eo H$mohm b ( monoZm b) | ~y X -~y X H$aHo$ 5% jmar nmoQ> {e na JZoQ> {db Z { bm m OmVm h ? amgm {ZH$ g rH$aU H$s ghm Vm go m m H$s{OE & 2 What happens when 5% alkaline potassium permanganate solution is added drop by drop to warm propyl alcohol (propanol) taken in a test tube ? Explain with the help of a chemical equation. ^mJ g SECTION C 6. Ordm m h H$s{OE & ? Ordm m| H$s Am w {ZYm aU H$aZo H$s Xmo {d{Y`m| H$m g jon | dU Z 3 What are fossils ? Describe briefly two methods of determining the age of fossils. 7. H$m M Ho$ { go Jw OaZo dmbo doV H$me Ho$ {djonU H$m m H$maU h ? EH$ X gao Ho$ gmnoj EH$ gmW C Q>r p W{V | aIo Xmo gd g H$m M Ho$ { m| Ho$ {H$gr $bH$ na {V H$V: Amn{VV doV H$me Ho$ hrZ nw O Ho$ nW H$mo Xem Zo Ho$ {bE {H$aU AmaoI It{ME & AWdm H$me H$m H$sU Z m h ? Bg n[aKQ>Zm H$m Cn moJ H$aHo$ m m H$s{OE {H$ (i) gy m}X Ho$ g gy a Vm^ m| VrV hmoVm h , VWm (ii) d N> AmH$me Zrbm m| VrV hmoVm h & 31/4/1 3 3 3 P.T.O. What is the cause of dispersion of white light through a glass prism ? Draw a ray diagram to show the path of light when two identical glass prisms are arranged together in inverted position with respect to each other and a narrow beam of white light is allowed to fall obliquely on one of the faces of the prisms. OR What is scattering of light ? Use this phenomenon to explain why (i) the Sun appears reddish at sun-rise, and (ii) the clear sky appears blue. 8. (a) {Z Z{b{IV A{^{H $ mAm| H$m {d{^ H$mam| | dJuH$aU H$s{OE : (i) AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq) (ii) CaO(s) + H2O(l) Ca(OH)2(aq) (iii) 2KClO3(s) 2KCl(aq) + 3O2(g) (iv) Zn + CuSO4 ZnSO4 + Cu (b) {Z Z{b{IV H$WZ H$mo g Vw{bV amgm {ZH$ g rH$aU Ho$ $n | $nm V[aV H$s{OE : ~o[a bmoamBS>, Eobw{ {Z g o$Q> go A{^{H $ m H$aHo$ Eobw{ {Z bmoamBS> Am a ~o[a g o$Q> ~ZmVm h & AWdm O~ {H$gr naIZbr | boS> (II) ZmBQ >oQ> H$m {db Z boH$a Cg | nmoQ>{ e Am moS>mBS> H$m {db Z { bmVo h , Vmo H$moB Adjon ~ZVm h & (a) Bg Adjon H$m m a J hmoVm h ? Adjo{nV m {JH$ H$m Zm {b{IE & (b) Bg A{^{H $ m H$m g Vw{bV amgm {ZH$ g rH$aU {b{IE & (c) A{^{H $ m Ho$ CZ Xmo H$mam| H$s gyMr ~ZmBE {OZ | Bg A{^{H $ m H$mo aIm Om gH$Vm h & (a) 31/4/1 Classify the following reactions into different types : (i) AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq) (ii) CaO(s) + H2O(l) Ca(OH)2(aq) (iii) 2KClO3(s) 2KCl(aq) + 3O2(g) (iv) Zn + CuSO4 ZnSO4 + Cu 4 3 3 (b) Translate the following statement into a balanced chemical equation : Barium chloride reacts with aluminium sulphate to give aluminium chloride and barium sulphate. OR When potassium iodide solution is added to a solution of lead (II) nitrate in a test tube, a precipitate is formed. (a) What is the colour of this precipitate ? Name the compound precipitated. 9. (b) Write the balanced chemical equation for this reaction. (c) List two types of reactions in which this reaction can be placed. (a) mH ${VH$ Obme m| H$s {Z { V g $mB Zht H$s OmVr O~{H$ ObOrdembmAm| H$mo {Z { V g $mB H$s Amd H$Vm hmoVr h & m| ? (b) AnKQ>H$ m h ? {X {H$gr nm[aV go AnKQ>H$m| H$m nyU $n go C ybZ H$a {X m OmE, Vmo BgH$m m n[aUm hmoJm ? AnZo C ma Ho$ g_Y Z _| nwp Q> H$s{OE & AWdm dm w S>b Ho$ C Va Va na Amo OmoZ {H$g H$ma ~ZVr h ? BgHo$ h d H$m C oI H$s{OE & BgHo$ mg Ho$ {bE H$m Z C maXm r h ? Amo OmoZ- mg H$m EH$ hm{ZH$a ^md {b{IE & (a) Natural water bodies are not regularly cleaned whereas an aquarium needs regular cleaning. Why ? (b) What are decomposers ? What will be the consequence if the decomposers are completely eradicated from an ecosystem ? Give justification in support of your answer. 3 3 OR How is ozone formed in the upper atmosphere ? State its importance. What is responsible for its depletion ? Write one harmful effect of ozone depletion. 31/4/1 5 P.T.O. 10. Qy>Q>r-h{ > m| H$mo ghmam XoZo Ho$ {bE S>m Q>a {H$gr doV nmCS>a H$m Cn moJ H$aVo h & (a) Bg nmCS>a H$m Zm Am a amgm {ZH$ gy {b{IE & (b) Bg nmCS>a H$mo {H$g H$ma ~Zm m OmVm h ? (c) O~ Bg doV nmCS>a H$mo nmZr Ho$ gmW Jy Wm OmVm h , Vmo EH$ H$R>moa R>mog {n S> m V hmoVm h & Bg n[adV Z Ho$ {bE g Vw{bV amgm {ZH$ g rH$aU {b{IE & (d) Bg doV nmCS>a H$m H$moB EH$ Am a Cn moJ {b{IE & 3 A white powder is used by doctors to support fractured bones. 11. (a) Write the name and chemical formula of the powder. (b) How is this powder prepared ? (c) When this white powder is mixed with water, a hard solid mass is obtained. Write a balanced chemical equation for the change. (d) Give one more use of this white powder. {d wV amoYr Vm ~o Ho$ Vma H$s H$moB Hw$ S>br {H$gr J doZmo rQ>a go g mo{OV h & m hmoJm O~ {H$gr ~b N> S> Mw ~H$ H$mo (a) Hw$ S>br Ho$ ^rVa YHo$bm OmEJm ? (b) Hw$ S>br go ~mha bm m OmEJm ? (c) Hw$ S>br Ho$ ^rVa p Wa aIm OmEJm ? oH$ ojU H$s H$maU g{hV nwp Q> H$s{OE & A coil of insulated copper wire is connected to a galvanometer. What would happen if a strong bar magnet is (a) pushed into the coil ? (b) withdrawn from inside the coil ? (c) held stationary inside the coil ? Give justification for each observation. 12. (a) 31/4/1 mZd Amhma Zmb | {Z Z{b{IV Ho$ H$m {b{IE : (i) bma (bmbm ag) (ii) Am me | HCl (iii) {n m ag (iv) XrK amo_ 6 3 (b) (a) (b) 13. (a) (b) (a) (b) 14. {Z Z{b{IV E OmB m| | oH$ H$m EH$ H$m {b{IE : (i) nop gZ (ii) bmBno O 3 Write the function of the following in the human alimentary canal : (i) Saliva (ii) HCl in stomach (iii) Bile juice (iv) Villi Write one function each of the following enzymes : (i) Pepsin (ii) Lipase nmXnm| (nm Ym|) | V { H$m V Zht hmoVm, { $a ^r, {X h {H$gr g doXZerb nmXn H$mo ne H$aVo h , Vmo CgH$s n{ m m| | ojU H$aZo mo n[adV Z hmoVo h & m m H$s{OE {H$ h nmXn ~m C rnZ Ho$ gmW {H$g H$ma AZw{H $ m H$aVm h Am a h AZw{H $`m {H$g H$ma g Mm[aV hmoVr h & Cg hm m}Z H$m Zm {b{IE {OgH$mo {Z Z{b{IV Ho$ {bE {X m OmVm h : (i) {H$gr ~m Zo nm Yo H$s b ~mB | d { Ho$ {bE & (ii) $bm| Am a ~rOm| | H$mo{eH$m {d^mOZ H$mo Vrd H$aZo Ho$ {bE & 3 Plants do not have any nervous system but yet, if we touch a sensitive plant, some observable changes take place in its leaves. Explain how could this plant respond to the external stimuli and how it is communicated. Name the hormone that needs to be administered to (i) increase the height of a dwarf plant. (ii) cause rapid cell division in fruits and seeds. O d {d{dYVm {H$go H$hVo h ? dZm| H$mo O d {d{dYVm Ho$ {bE {d{e Q> Wb m| mZm OmVm h ? dZmo ybZ Ho$ {bE C maXm r Xmo H$maH$m| H$s gyMr ~ZmBE & 3 What is biodiversity ? Why are forests considered as biodiversity hot spots ? List two factors responsible for causing deforestation. 15. g{H $ Vm loUr | g~go D$na p WV YmVwAm| Ho$ {Z H$f U H$s {d{Y, g{H $ Vm loUr Ho$ | p WV YmVwAm| Ho$ {Z H$f U H$s {d{Y go {H$g H$ma {^ h ? CZHo$ {bE ^r g mZ {H $ m m| Zht AnZm r OmVr h ? BZ YmVwAm| Ho$ {Z H$f U H$s {H $ m H$m Zm {b{IE & 3 How is the method of extraction of metals high up in the reactivity series different from that for metals in the middle ? Why can the same process not be applied for them ? Name the process used for the extraction of these metals. 31/4/1 7 P.T.O. ^mJ X SECTION D 16. (a) E Q>arH$aU Am a gm~wZrH$aU A{^{H $ mAm| Ho$ ~rM, oH$ Ho$ {bE amgm {ZH$ g rH$aUm| H$s ghm Vm go, {d^oXZ H$s{OE & (b) Zm m {H$V AmaoI Ho$ gmW E Q>a ~ZmZo Ho$ EH$ {H $ mH$bmn H$m g jon | dU Z H$s{OE & AWdm gm~wZ Am a An mO H$ | m A Va h ? {H$gr d na bJo {MH$ZmB Ho$ Y ~o H$mo hQ>mZo | gm~wZ H$s g $mB {H $ m H$m g jon | C oI H$s{OE & O~ d H$mo H$R>moa Ob | YmoZm hmoVm h , Vmo gm~wZ H$m Cn moJ ~h V ^mdr m| Zht hmoVm ? Bg g m H$m g mYmZ {H$g H$ma {H$ m OmVm h ? (a) Distinguish between esterification and saponification reactions with the help of chemical equations for each. (b) With a labelled diagram describe in brief an activity to show the 5 5 formation of an ester. OR What is the difference between soaps and detergents ? State in brief the cleansing action of soaps in removing an oily spot from a fabric. Why are soaps not very effective when a fabric is washed in hard water ? How is this problem resolved ? 17. H$moB { V AnZo Zo m| go 50 cm go H$ X ar H$s d VwAm| H$mo n Q> Zht XoI nmVm & (a) Bg { V Ho$ p Q> Xmof H$m Zm {b{IE Am a Bg Xmof Ho$ Xmo g ^m{dV H$maUm| H$s gyMr ~ZmBE & (b) Cn`w V H$aU | Xmof H$mo Xem Zo Ho$ {bE {H$aU AmaoI It{ME & (c) Bg Xmof Ho$ g emoYZ Ho$ {bE CgHo$ mam Cn moJ {H$E OmZo dmbo b|g H$m H$ma {b{IE Am a CgH$s j Vm n[aH${bV H$s{OE & mZ br{OE {H$ gm m Zo H$m {ZH$Q> {~ X 25 cm h & (d) Cn`w V H$aU | p Q> Xmof Ho$ g emoYZ Ho$ {bE Zm_m {H$V AmaoI It{ME & 31/4/1 8 5 A person is unable to see objects distinctly placed within 50 cm from his eyes. (a) Name the defect of vision the person is suffering from and list its two possible causes. (b) Draw a ray diagram to show the defect in the above case. (c) Mention the type of lens used by him for the correction of the defect and calculate its power. Assume that the near point for the normal eye is 25 cm. (d) Draw a labelled diagram for the correction of the defect in the above case. 18. (a) (b) {X {H$gr V d H$m Bbo Q >m {ZH$ {d mg kmV h , Vmo CgH$s g moOH$Vm {H$g H$ma {ZYm [aV H$s OmVr h ? Cg V d H$s g moOH$Vm {ZYm [aV H$s{OE {OgH$m na mUw H $_m H$ 9 h & ZrMo AmYw{ZH$ AmdV gmaUr Ho$ Hw$N> V d {XE JE h & BZ V dm| H$m na mUw H $_m H$ H$mo R>H$ | {X`m J`m h : A(4), B(9), C(14), D(19), E(20) (i) (ii) (iii) (a) (b) 5 How is the valency of an element determined if its electronic configuration is known ? Determine the valency of an element of atomic no. 9. Given below are some elements of the Modern Periodic Table. Atomic numbers of the elements are given in parentheses : (i) (ii) (iii) 31/4/1 Bbo Q >m {ZH$ {d mg H$s ghm Vm go kmV H$s{OE {H$ BZ | go {H$g V d Ho$ ~m V H$moe | EH$ Bbo Q >m Z h & H$m Z-go Xmo V d g mZ g yh (J wn) Ho$ h ? AnZo C ma Ho$ g W Z | H$maU Xr{OE & Cn`w V V dm| | go Mm Wo AmdV Ho$ {H$g V d H$s na mp dH$ { m ~ S>r h Am a m| ? A(4), B(9), C(14), D(19), E(20) With the help of the electronic configuration, find out which one of the above elements will have one electron in its outermost shell. Which two elements belong to the same group ? Give reasons for your answer. Which one of the above elements belonging to the fourth period has bigger atomic radius and why ? 9 P.T.O. 19. (a) (b) {d wV e{ V H$s n[a^mfm Xr{OE & dmo Q>Vm V Ho$ moV Ho$ {gam| go g mo{OV R {VamoY H$m H$moB {d wV gm{Y Ymam I boVm h & Ymam Am a {VamoY Ho$ nXm| | e{ V Ho$ {bE OH$ w n H$s{OE & 100 W; 220 V Am a 60 W; 220 V AZw Vm H$ Ho$ Xmo {d wV ~ ~ nm d | 220 V Ho$ {d wV |g go g mo{OV h & ~ ~m| mam |g go br J r Ymam kmV H$s{OE & 5 AWdm (a) (b) {H$gr moJ H$s ghm Vm go Amn h {Z H$f {H$g H$ma {ZH$mb|Jo {H$ V dmo Q> H$s {H$gr ~ Q>ar go loUrH $ | g mo{OV VrZ {VamoYH$m| R1, R2 Am a R3 Ho$ n[anW Ho$ oH$ ^mJ go g mZ Ymam dm{hV hmoVr h ? ZrMo {XE JE n[anW H$m A Z H$aHo$, {Z Z{b{IV kmV H$s{OE : (i) (ii) 12 {VamoYH$ go dm{hV Ymam & A1 Am a A2 Ho$ nmR> m H$m| | A Va, {X H$moB h & (a) Define electric power. An electrical device of resistance R is connected across a source of voltage V and draws a current I. Derive an expression for power in terms of current and resistance. (b) Two electric bulbs rated 100 W; 220 V and 60 W; 220 V are connected in parallel to an electric mains of 220 V. Find the current drawn by the bulbs from the mains. OR 31/4/1 10 5 (a) How will you infer with the help of an experiment that the same current flows through every part of the circuit containing three resistors R1, R2 and R3 in series connected to a battery of V volts ? (b) 20. Study the following circuit and find out : (i) Current in 12 resistor. (ii) Difference in the readings of A1 and A2, if any. (a) H$m{ H$ dY Z H$s n[a^mfm {b{IE & BgH$s Xmo {d{Y m| H$s gyMr ~ZmBE & (b) Hw$N> H$ma Ho$ nmXnm| H$mo CJmZo Ho$ {bE Bg {dYm H$m Cn moJ m| {H$ m OmVm h ? (c) Zm m {H$V AmaoIm| H$s ghm Vm go hmBS >m | wHw$bZ H$s {H $ m H$s m m H$s{OE & AWdm J^ {ZamoY {H$go H$hVo h ? BgH$s Mma {d{^ {d{Y m| H$s gyMr ~ZmBE & J^ {ZamoYH$ w{ V m AnZmZo Ho$ Mma g ^d H$maU {b{IE & (a) Define vegetative propagation. List its two methods. (b) Why is this mode practised for growing some types of plants ? (c) Explain the process of budding in Hydra with the help of labelled diagrams. 5 5 OR What is contraception ? List its four different methods. State four reasons for adopting contraceptive methods. 31/4/1 11 P.T.O. 21. (a) (b) Q>a Ho$ CZ Xmo Wyb $n go {XImB XoZo dmbo bjUm| H$s gyMr ~ZmBE {OZH$m A Z |S>b Zo AnZo moJm| | {H$ m Wm & |S>b Ho$ moJm| mam H $go nVm Mbm {H$ bjU ^mdr AWdm A ^mdr hmoVo h ? dmh AmaoI H$s ghm Vm go Amn h H $go Wm{nV H$a|Jo {H$ mZd | {H$gr ZdOmV H$m qbJ {dew $n go m g moJ h Am a mVm-{nVm | go {H$gr H$mo ^r, ZdOmV Ho$ {H$gr {deof qbJ Ho$ {bE, C maXm r Zht mZm Om gH$Vm h ? (a) List two visible traits of garden pea that Mendel considered in his experiments. How do Mendel s experiments show that traits may be dominant or recessive ? (b) With the help of a flow diagram, how would you establish that in human beings the sex of a newborn is purely a matter of chance and none of the parents may be considered responsible for a particular sex of a newborn child ? 5 ^mJ SECTION E 22. H$moB N>m ~o[a bmoamBS> nmCS>a | gmo{S> g o$Q> nmCS>a { bmVm h & BZ XmoZm| nmCS>am| H$mo { bmZo na dh N>m m n[adV Z ojU H$aoJm ? AnZo C ma H$s nwp Q> H$s{OE Am a m m H$s{OE {H$ dh dm {N>V n[adV Z {H$g H$ma m V H$a gH$Vm h & AWdm (a) {Z Z{b{IV YmVwAm| H$mo CZH$s A{^{H $ merbVm Ho$ Amamohr (~ T>Vo) H $ | dp WV H$s{OE : H$m na, q OH$, Eobw{ {Z VWm Am aZ (b) H$m na g o$Q> {db Z | bmoho H$s aoVZ { bmZo Ho$ 30 { ZQ> Ho$ n MmV AnZr ZmoQ>~wH$ | gyMr~ {H$E OmZo dmbo Xmo ojUm| H$s gyMr ~ZmBE & A student mixes sodium sulphate powder in barium chloride powder. What change would the student observe on mixing the two powders ? Justify your answer and explain how he can obtain the desired change. OR (a) Arrange the following metals in the increasing order of their reactivities : Copper, Zinc, Aluminium and Iron (b) List two observations you would record in your notebook 30 minutes after adding iron filings to copper sulphate solution. 31/4/1 12 2 2 23. H$moB {db Z X pH n na CgH$s H$moB ~ yX {JamZo na Zma Jr a J XoVm h , O~{H$ H$moB A {db Z Y pH n na CgH$s ~y X {JamZo na h H$m Zrbm a J XoVm h & BZ XmoZm| {db Zm| H$s H ${V `m h ? X Am a Y {db`Zm| Ho$ pH {ZYm [aV H$s{OE & 2 A solution X gives orange colour when a drop of it falls on pH paper, while another solution Y gives bluish colour when a drop of it falls on pH paper. What is the nature of both the solutions ? Determine the pH of solutions X and Y . 24. {Z Z{b{IV {H$aU AmaoI H$m A Z H$s{OE Am a Bgo ItMZo | N>m mam H$s J r Xmo w{Q> m| H$s gyMr ~ZmBE & {~ ~ AB H$s p W{V Ho$ VXZw $n ~ZZo dmbo {V{~ ~ H$s dm V{dH$ p W{V Am a gmB O H$mo Xem Zo Ho$ {bE ghr {H$aU AmaoI ItMH$a BZ w{Q> m| H$mo g emo{YV H$s{OE & 2 AWdm {H$gr N>m H$mo {H$gr H$m M Ho$ { go Jw OaZo dmbr {H$aU H$m nW Amao{IV H$aZm h & A N>o n[aUm m V H$aZo Ho$ {bE CgHo$ mam ~aVr OmZo dmbr Mma gmdYm{Z m| H$s gyMr ~ZmBE & 2 Study the following ray diagram and list two mistakes committed by the student while tracing it. Rectify these mistakes by drawing the correct ray diagram to show the real position and size of the image corresponding to the position of the object AB. OR A student has to trace the path of a ray of light through a glass prism. List four precautions he should observe for better results. 31/4/1 13 P.T.O. 25. {H$gr {VamoYH$ Ho$ {gam| na {d^dm Va H$s Cggo dm{hV {d wV Ymam na {Z^ aVm H$m A Z H$aZo Ho$ {bE {Z Z{b{IV H$m Z-gr d Wm (n[anW) ghr h Am a m| ? A B C 2 D Which one of the following is the correct set-up for studying the dependence of the current on the potential difference across a resistor and why ? A 26. B C D a Y m| H$mo Xem Zo Ho$ {bE {H$gr n mr H$s {P r H$m A Wm r AmamohU V ma H$aZm moJ H$s {d{Y Ho$ H $ dma Mma MaU {b{IE & AWdm A Hw$[aV hmoVo ~rO H$m~ Z S>mBAm gmBS> N>mo S>Vo h , Bgo Xem Zo H$s m mo{JH$ d Wm go g ~ {YV {Z Z{b{IV Zm| Ho$ C ma Xr{OE : (i) h e dmH$ma bm H$ H$mo dm w m| aIVo h ? 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