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CBSE Class 12 Board Exam 2019 : Chemistry (Series 3)

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SET-1 H$moS> Z . Series BVM/3 Code No. amob Z . 56/3/1 narjmWu H$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. agm`Z {dkmZ (g mp VH$) CHEMISTRY (Theory) {ZYm [aV g_` : 3 K Q>o A{YH$V_ A H$ : 70 Time allowed : 3 hours 56/3/1 Maximum Marks : 70 1 P.T.O. gm_m ` {ZX}e : (i) g^r Z A{Zdm` h & (ii) I S> A : Z g `m 1 go 5 VH$ A{V bKw-C mar` Z h Am a `oH$ Z Ho$ {bE 1 A H$ h & (iii) I S> ~ : Z g `m 6 go 12 VH$ bKw-C mar` Z h Am a `oH$ Z Ho$ {bE 2 A H$ h & (iv) I S> g : Z g `m 13 go 24 VH$ ^r bKw-C mar` Z h Am a `oH$ Z Ho$ {bE 3 A H$ h & (v) I S> X : Z g `m 25 go 27 VH$ XrK -C mar` Z h Am a `oH$ Z Ho$ {bE 5 A H$ h & (vi) Z n _| g_J {dH$ n Zht {X`m J`m h & {\$a ^r EH$ A H$ dmbo Xmo Zm| _|, Xmo A H$m| dmbo Xmo Zmo _|, VrZ A H$m| dmbo Mma Zm| _| VWm nm M A H$m| dmbo VrZm| Zm| _| {dH$ n {X`m J`m h & Eogo g^r Zm| _| go AmnH$mo EH$ hr {dH$ n H$m C ma XoZm h & (vii) `{X Amd `H$Vm hmo, Vmo Amn bKwJUH$s` gma{U`m _m J gH$Vo h & H $ Hw$boQ>am| Ho$ `moJ H$s AZw_{V Zht h & General Instructions : (i) All questions are compulsory. (ii) Section A : Questions number 1 to 5 are very short answer questions and carry 1 mark each. (iii) Section B : Questions number 6 to 12 are short answer questions and carry 2 marks each. (iv) Section C : Questions number 13 to 24 are also short answer questions and carry 3 marks each. (v) Section D : Questions number 25 to 27 are long answer questions and carry 5 marks each. (vi) There is no overall choice. However, an internal choice has been provided in two questions of one mark, two questions of two marks, four questions of three marks and all the three questions of five marks weightage. You have to attempt only one of the choices in such questions. (vii) Use of log tables, if necessary. Use of calculators is not allowed. 56/3/1 2 I S> A SECTION A 1. {Z Z{b{IV `m {JH$ H$m AmB .`y.nr.E.gr. Zm_ {b{IE : 1 Write the IUPAC name of the following compound : 2. {Z Z{b{IV H$mo CZHo$ A br` bjU Ho$ ~ T>Vo h E H $_ _| `dp WV H$s{OE ~o OmoBH$ A b, \$sZm b, H $sgm b : 1 Arrange the following in increasing order of their acidic character : Benzoic acid, Phenol, Cresol 3. g Hw$b [Co(en)2(H2O)(CN)]2+ H$m AmB .`y.nr.E.gr. Zm_ {b{IE & AWdm A_mo{Z`_ Q>oQ >m bmo[aS>moH$mo~m Q>oQ>(II) H$m AmB .`y.nr.E.gr. _mZX S>m| H$m Cn`moJ H$aVo h E gy {b{IE & 1 1 Write IUPAC name of the complex [Co(en)2(H2O)(CN)]2+. OR Using IUPAC norms, write the formula of Ammonium tetrafluoridocobaltate(II). 4. bmBH$mogmBS>r ~ Y Am a no Q>mBS> ~ Y Ho$ ~rM `m A Va h ? AWdm `yp b`moQ>mBS> Am a `yp b`mogmBS> Ho$ ~rM `m A Va h ? 1 1 What is the difference between a glycosidic linkage and a peptide linkage ? OR What is the difference between Nucleotide and Nucleoside ? 5. ? Why is chloroform kept in dark coloured bottles ? bmoamo\$m _ H$mo Jm T>r a JrZ ~moVbm| _| `m| aIm OmVm h 56/3/1 3 1 P.T.O. I S> ~ SECTION B 6. `m hmoVm h O~ AgCl H$mo CdCl2 go S>mo{nV {H$`m OmVm h ? Bg Xmof H$m `m Zm_ h AWdm (a) Q>m B{H$`mo_rQ >r Xmofm|, Am a (b) Zm Z- Q>m B{H$`mo_rQ >r Xmofm| _| NaCl mam {H$g H$ma H$m Xmof Xem `m OmVm h ? ? 2 2 What happens when AgCl is doped with CdCl2 ? What is the name of this defect ? OR What type of defect is shown by NaCl in (a) stoichiometric defects, and (b) non-stoichiometric defects ? 7. (a) (b) (a) (b) byH$mog Ho$ 0 1 _mobb Obr` {db`Z Am a KCl Ho$ 0 1 _mobb Obr` {db`Z _| go {H$gH$m dWZm H$ C MVa hmoJm Am a `m| ? mJw{ $ H$s{OE {H$ {Z Z{b{IV _| dm Q> hm \$ JwUH$, (i) EH$ go H$_ AWdm EH$ go A{YH$ h : (i) Ob _| {db{`V CH3COOH (ii) ~o OrZ _| {db{`V CH3COOH Out of 0 1 molal aqueous solution of glucose and 0 1 molal aqueous solution of KCl, which one will have higher boiling point and why ? Predict whether van t Hoff factor, (i) is less than one or greater than one in the following : (i) CH3COOH dissolved in water (ii) 8. CH3COOH dissolved in benzene {Z Z{b{IV g_rH$aUm| H$mo nyU Ed g Vw{bV H$s{OE : (a) C + H2SO4 (gm ) (b) 2 XeF2 + PF5 AWdm {Z Z{b{IV A{^{H $`mAm| go g ~ g Vw{bV amgm`{ZH$ g_rH$aU {b{IE : (a) bwAmoarZ J g Ob go A{^{H $`m H$aVr h & (b) \$m \$sZ J g H$m na g \o$Q> {db`Z _| Ademo{fV H$s OmVr h & 56/3/1 2 4 2 Complete and balance the following equations : (a) C + H2SO4 (conc.) (b) XeF2 + PF5 OR Write balanced chemical equations involved in the following reactions : (a) Fluorine gas reacts with water. (b) Phosphine gas is absorbed in copper sulphate solution. 9. 2 {Z Z{b{IV H$s g aMZmE It{ME : (a) H2S2O7 (b) HClO3 Draw structures of the following : (a) H2S2O7 (b) HClO3 10. ew H$ gob _| EoZmoS> Am a H $WmoS> na hmoZo dmbr A{^{H $`mE {b{IE & ew H$ gob, _ `y ar gob go {H$g H$ma {^ h ? 2 Write anode and cathode reactions that occur in dry cell. How does a dry cell differ from a mercury cell ? 11. {Z Z{b{IV Ho$ {bE H$maU {b{IE : (a) Eoamo_o{Q>H$ mW{_H$ Eo_rZ ~ZmZo Ho$ {bE J {~ Eb W {b_mBS> g bofU H$mo dar`Vm Zht Xr OmVr & (b) ~o OrZ g \$mo{Zb bmoamBS> Ho$ gmW A{^{H $`m H$aHo$, mW{_H$ Eo_rZ jma _| {dbo` C nmX XoVm h O~{H$ { Vr`H$ Eo_rZ jma _| A{dbo` C nmX XoVm h & 2 Account for the following : (a) Gabriel phthalimide synthesis is not preferred for preparing aromatic primary amines. (b) On reaction with benzene sulphonyl chloride, primary amine yields product soluble in alkali whereas secondary amine yields product insoluble in alkali. 12. {Z Z{b{IV `oH$ A{^{H $`m _| `m {JH$m| 56/3/1 A Am a 5 B H$s g aMZmE {b{IE : 2 P.T.O. Write structures of compounds A and B in each of the following reactions : I S> g SECTION C 13. (a) {H$gr gob _| {Z Z{b{IV A{^{H $`m hmoVr h : Zn (s) + Ag2O (s) + H2O (l) Zn2+ (aq) + 2Ag (s) + 2OH (aq) A{^{H $`m Ho$ {bE rGo n[aH${bV H$s{OE & [{X`m J`m h : E o 2 = 0 76 V, (Zn Eo ( Ag / Ag ) (b) (a) / Zn) = 0 80 V, 1 F = 96,500 C mol 1] Amn ~b {d wV -AnKQ> Am a X ~ b {d wV -AnKQ> H$s gr_m V _moba MmbH$Vm, o ( m ) H $go kmV H$a gH$Vo h ? 3 Following reaction takes place in the cell : Zn (s) + Ag2O (s) + H2O (l) Zn2+ (aq) + 2Ag (s) + 2OH (aq) Calculate rGo of the reaction. [Given : E o 2 = 0 76 V, (Zn / Zn) Eo ( Ag / Ag ) (b) 14. = 0 80 V, 1 F = 96,500 C mol 1] o How can you determine limiting molar conductivity, ( m ) for strong electrolyte and weak electrolyte ? {Z Z{b{IV H$mo C{MV CXmhaU g{hV n[a^m{fV H$s{OE : (a) H $XZ (b) ~h Amp dH$ H$mobm BS> (c) Oob AWdm 56/3/1 6 3 (a) (b) (c) Q>mM Am a \o$[aH$ hmBS >m gmBS> gm b _| go H$m Z-gm AmgmZr go H ${XV {H$`m Om gH$Vm h Am a `m| ? {H$gr B_ eZ H$m AnHo$ U {H$E OmZo na `m o{jV hmoVm h ? C oaU _| dY H$ Am a {df H$s `m ^y{_H$m h ? 3 Define the following with a suitable example, of each : (a) Coagulation (b) Multimolecular colloid (c) Gel OR 15. (a) Out of starch and ferric hydroxide sol, which one can easily be coagulated and why ? (b) What is observed when an emulsion is centrifuged ? (c) What is the role of promoters and poisons in catalysis ? (a) H$moB V d 3 10 8 cm H$mop R>H$m H$moa Ho$ gmW A V:Ho$p V KZ (bcc) OmbH$ _| {H $ Q>brH $V hmoVm h & V d H$m KZ d 6 89 g cm 3 h & V d H$m _moba `_mZ n[aH${bV H$s{OE & (NA = 6 022 1023 mol 1) {H$g H$ma H$m AY MmbH$ m hmoVm h O~ (i) Ge H$mo In go S>mo{nV {H$`m OmVm h ? (ii) Si H$mo P go S>mo{nV {H$`m OmVm h ? (b) 16. (a) An element crystallises in bcc lattice with a cell edge of 3 10 8 cm. The density of the element is 6 89 g cm 3. Calculate the molar mass of the element. (NA = 6 022 1023 mol 1) (b) What type of semiconductor is obtained when (i) Ge is doped with In ? (ii) Si is doped with P ? Na2SO4 H$m 0 1 M {db`Z 95% H$s gr_m VH$ KwbZerb h & BgH$m namgaU Xm~ `m hmoJm ? (R = 0 0821 L atm K 1 mol 1) 27 C 3 na 3 A solution 0 1 M of Na2SO4 is dissolved to the extent of 95%. What would be its osmotic pressure at 27 C ? (R = 0 0821 L atm K 1 mol 1) 56/3/1 7 P.T.O. 17. Am`aZ YmVwH${_ H$s go g ~ {YV dm `m ^ >r _| 500 K 800 K Vmn n[aga _| hmoZo dmbr A{^{H $`mE {b{IE & Am`aZ H$s YmVwH${_ H$s _| MyZm n Wa H$s `m ^y{_H$m h ? AWdm `m hmoVm h O~ (a) dm`w H$s Cnp W{V _| NaCN Ho$ gmW {g da H$m {ZjmbZ {H$`m OmVm h ? (b) {g{bH$m naV M T>o n[adV H$ _| H$m na _ Q> ^aZo Ho$ n MmV J_ dm`w Ho$ Pm|Ho$ dm{hV {H$E OmVo h ? (c) \o$Z bdZ {d{Y mam {H$gr A` H$ _| Cnp WV PbS Am a ZnS H$m gm U H$aVo g_` NaCN {_bm`m OmVm h ? 3 3 Write down the reactions taking place in blast furnace related to the metallurgy of iron in the temperature range 500 K 800 K. What is the role of limestone in the metallurgy of iron ? OR What happens when 18. (a) Silver is leached with NaCN in the presence of air ? (b) Copper matte is charged into silica lined converter and hot air blast is blown ? (c) NaCN is added in an ore containing PbS and ZnS during concentration by froth floatation method ? 3 {Z Z{b{IV Ho$ {bE H$maU Xr{OE : (a) S>mBAm grOZ EH$ J g h O~{H$ g \$a EH$ R>mog h & (b) OoQ> {d_mZm| go C g{O V (c) ew h bmoOZm| H$s Anojm A Vam-h bmoOZ| A{YH$ A{^{H $`merb h & NO (g) Amo OmoZ naV H$m _ X J{V go jaU H$a ahr h & Give reasons for the following : (a) Dioxygen is a gas but sulphur a solid. (b) NO (g) released by jet aeroplanes is slowly depleting the ozone layer. (c) Interhalogens are more reactive than pure halogens. 56/3/1 8 19. 3 {Z Z{b{IV ~h bH$m| H$mo m H$aZo Ho$ {bE `w $ EH$bH$m| H$s g aMZmE {b{IE : (a) {ZAmo rZ (b) PHBV (c) ~ Ho$bmBQ> (a) (b) (c) AWdm {Z Z{b{IV ~h bH$m| H$mo CZHo$ A VamAmp dH$ ~bm| Ho$ KQ>Vo h E H $_ _| `dp WV H$s{OE : ~ Ho$bmBQ>, nm {bWrZ, `yZm-S, ZmBbm Z-6,6 {Z Z{b{IV ~h bH$ Ho$ EH$bH$m| H$mo {b{IE : C KZ d nm {bWrZ (HDP) Am a A n KZ d nm {bWrZ g aMZm _H$ A Va `m h ? (LDP) Ho$ ~rM 3 Write the structures of monomers used to obtain the following polymers : (a) Neoprene (b) PHBV (c) Bakelite OR (a) Arrange the following polymers in decreasing order of their intermolecular forces : Bakelite, Polythene, Buna-S, Nylon-6,6 20. (b) Write the monomers of the following polymer : (c) What is the structural difference between high density polythene (HDP) and low density polythene (LDP) ? (a) {V-A bm o _| gmo{S>`_ hmBS >moOZ H$m~m oZoQ> H$s Anojm Ymp dH$ hmBS >m gmBS> ~ohVa {dH$ n `m| h ? {Xb Ho$ Xm ao amoH$Zo _| Eop n[aZ `m| `w $ hmoVr h ? {V{h Q> {_Z Am_me` Ho$ A b dU na ^md `m| Zht S>mbVr ? AWdm (b) (c) 56/3/1 9 3 P.T.O. 3 {Z Z{b{IV nXm| H$mo C{MV CXmhaU g{hV n[a^m{fV H$s{OE : (a) em VH$ (b) {VO {dH$ (Ep Q>~m`mo{Q>H$) (c) AZm`{ZH$ An_mO H$ (a) Why are metal hydroxides better alternatives than sodium hydrogen carbonate in antacids ? (b) Why is aspirin used in the prevention of heart-attacks ? (c) Why antihistamines do not affect the secretion of acid in stomach ? OR Define the following terms with a suitable example of each : 21. (a) Tranquilizers (b) Antibiotics (c) Non-ionic detergents (a) _| go, H$m Z-gm A{YH$ A{^{H $`merb h Am a `m| (b) A{^{H $`m Ho$ {V ? _| go, H$m Z-gm Zm{^H$ Zohr {V WmnZ A{^{H $`m Ho$ {V A{YH$ A{^{H $`merb h Am a `m| ? (c) (a) SN2 _| go H$m Z-gm Y wdU KyU H$ h Am a `m| Out of ? , which one is more reactive towards SN2 reaction and why ? (b) Out of , which one is more reactive towards nucleophilic substitution reaction and why ? (c) Out of , which one is optically active and why ? 56/3/1 10 3 22. `m hmoVm h O~ (a) g {b{g{bH$ A b H$s (CH3CO)2O/H+ Ho$ gmW A{^{H $`m H$s OmVr h (b) \$sZm b Na2Cr2O7/H+ go Am grH $V hmoVm h ? (c) Eo{Zgmob H$s CH3Cl/{ZO b AlCl3 Ho$ gmW A{^{H $`m H$s OmVr h ? AnZo C ma Ho$ g_W Z _| amgm`{ZH$ g_rH$aU {b{IE & ? 3 What happens when (a) Salicylic acid is treated with (CH3CO)2O/H+ ? (b) Phenol is oxidised with Na2Cr2O7/H+ ? (c) Anisole is treated with CH3Cl/anhydrous AlCl3 ? Write chemical equation in support of your answer. 23. (a) (b) (c) (a) Give one chemical test as an evidence to show that [Co(NH3)5Cl]SO4 and [Co(NH3)5(SO4)]Cl are ionisation isomers. (b) [NiCl4]2 is paramagnetic while [Ni(CO)4] is diamagnetic though both are tetrahedral. Why ? (Atomic no. of Ni = 28) Write the electronic configuration of Fe(III) on the basis of crystal field theory when it forms an octahedral complex in the presence of (i) strong field ligand, and (ii) weak field ligand. (Atomic no. of Fe = 26) (c) 24. [Co(NH3)5Cl]SO4 Am a [Co(NH3)5(SO4)]Cl Am`ZZ g_md`d h Bgo Xem Zo Ho$ {bE _mU Ho$ $n _| EH$ amgm`{ZH$ narjU Xr{OE & [NiCl4]2 AZwMw ~H$s` h O~{H$ [Ni(CO)4] {VMw ~H$s` h ` {n XmoZm| MVw \$bH$s` h & `m| ? (Ni H$m na_mUw H $_m H$ = 28) {H $ Q>b jo {g m V Ho$ AmYma na Fe(III) H$m Bbo Q >m {ZH$ {d `mg {b{IE O~ `h (a) ~b jo {bJ S>, Am a (b) X ~ b jo {bJ S> H$s Cnp W{V _| A Q>\$bH$s` g Hw$b ~ZmVm h & (Fe H$m na_mUw H $_m H$ = 26) `oH$ Ho$ {bE Cn`w $ CXmhaU g{hV {Z Z{b{IV nXm| H$mo n[a^m{fV H$s{OE : (a) EoZmo_a (b) Amd `H$ Eo_rZmo A b (c) moQ>rZ H$m {dH $VrH$aU 3 3 Define the following terms with a suitable example of each : (a) Anomers (b) Essential amino acids (c) Denaturation of protein 56/3/1 11 P.T.O. I S> X SECTION D 25. (a) (b) (a) (b) (a) Define order of reaction. How does order of a reaction differ from molecularity for a complex reaction ? (b) A first order reaction is 50% complete in 25 minutes. Calculate the time for 80% completion of the reaction. OR The decomposition of a hydrocarbon has value of rate constant as 2 5 104 s 1 at 27 C. At what temperature would rate constant be 7 5 104 s 1 if energy of activation is 19 147 103 J mol 1 ? (a) 26. A{^{H $`m H$s H$mo{Q> H$mo n[a^m{fV H$s{OE & {H$gr O{Q>b A{^{H $`m Ho$ {bE A{^{H $`m H$s H$mo{Q> Amp dH$Vm go {H$g H$ma {^ hmoVr h ? EH$ W_ H$mo{Q> H$s A{^{H $`m H$mo 50% nyU hmoZo _| 25 {_ZQ> bJVo h & A{^{H $`m H$mo 80% nyU hmoZo _| bJZo dmbo g_` H$m n[aH$bZ H$s{OE & AWdm 27 C na {H$gr hmBS >moH$m~ Z Ho$ {d`moOZ Ho$ {bE doJ p Wam H$ H$m _mZ 2 5 104 s 1 h & `{X g{H $`U D$Om 19 147 103 J mol 1 h , Vmo {H$g Vmn na doJ p Wam H$ 7 5 104 s 1 hmoJm ? EH$ n[ap W{V {b{IE {Og_| H$moB { Amp dH$ A{^{H $`m J{VH$V: W_ H$mo{Q> H$s hmo & Eogr A{^{H $`m H$m EH$ CXmhaU Xr{OE & ({X`m J`m h : log 2 = 0 3010, log 3 = 0 4771, log 5 = 0 6990) (b) Write a condition under which a bimolecular reaction is kinetically first order. Give an example of such a reaction. (Given : log 2 = 0 3010, log 3 = 0 4771, log 5 = 0 6990) (a) {Z Z{b{IV A{^{H $`mAm| Ho$ _w ` C nmX H$s mJw{ $ H$s{OE : 56/3/1 12 5 5 (c) (a) (b) hmBS >moOZ H$s A br` H ${V `m| hmoVr h ? AWdm O~ monoZ b {Z Z{b{IV A{^H$_ H$m| go A{^{H $`m H$aVm h V~ ~ZZo dmbo _w ` C nmX {b{IE : (i) ew H$ HCl H$s Cnp W{V _| CH3OH Ho$ Xmo _mob go (ii) VZw NaOH (iii) H2N NH2 Ho$ ~mX, E{WbrZ bmBH$m b _| nmoQ> {e`_ hmBS >m gmBS (KOH)> Ho$ gmW Ja_ H$aZo na $ {Z Z{b{IV `m {JH$m| H$mo B {JV JwUY_m o Ho$ ~ T>Vo h E H $_ _| `dp WV H$s{OE : H$m~m}{Zb `m {JH$m| Ho$ Eo \$m ( ) (i) F CH2COOH, O2N CH2COOH, CH3COOH, HCOOH (ii) A br` bjU EogrQ>moZ, EogrQ>p S>hmBS>, ~o O p S>hmBS>, EogrQ>mo\$sZmoZ HCN Ho$ g `moOZ Ho$ {V A{^{H $`merbVm (a) Predict the main product of the following reactions : (b) Give a simple chemical test to distinguish between (c) Why is alpha ( ) hydrogen of carbonyl compounds acidic in nature ? OR 56/3/1 13 5 5 P.T.O. (a) (b) 27. Write the main product formed when propanal reacts with the following reagents : (i) 2 moles of CH3OH in presence of dry HCl (ii) Dilute NaOH (iii) H2N NH2 followed by heating with KOH in ethylene glycol Arrange the following compounds in increasing order of their property as indicated : (i) F CH2COOH, O2N CH2COOH, CH3COOH, HCOOH acid character (ii) Acetone, Acetaldehyde, Benzaldehyde, Acetophenone reactivity towards addition of HCN (a) {Z Z{b{IV Ho$ {bE H$maU Xr{OE : (i) 3d loUr _| _ JZr O A{YH$V_ g `m _| Am grH$aU Ad WmE Xem Vm h & (ii) Mn3+/Mn2+ `w _ Ho$ {bE Eo H$m _mZ Cr3+/Cr2+ Ho$ _mZ go ~h V A{YH$ YZm _H$ hmoVm h & (iii) Obr` {db`Z _| Ti4+ a JhrZ h O~{H$ V4+ a JrZ h & (b) MnO2 (a) (b) (c) (d) (e) 56/3/1 go KMnO4 Ho$ {daMZ Ho$ {bE amgm`{ZH$ g_rH$aU {b{IE & ~ JZr a J H$m A brH $V na_ JZoQ> {db`Z a JhrZ `m| hmo OmVm h O~ `h Fe2+ H$m Fe3+ _| Am grH$aU H$aVm h ? AWdm g H $_U V dm| Am a p- bm H$ Ho$ V dm| H$s Am grH$aU Ad WmAm| H$s n[adV ZerbVm Ho$ g X^ _| EH$ {^ Vm {b{IE & g H $_U YmVwE H$UZ E W nr Ho$ C _mZ `m| Xem Vr h ? b WoZm `S> loUr Ho$ EH$ V d H$m Zm_ {b{IE Omo +4 Am grH$aU Ad Wm Xem Zo Ho$ {bE ^br-^m {V OmZm OmVm h & `m `h ~b Am grH$maH$ h AWdm AnMm`H$ ? b WoZm `S> AmHw $MZ `m h ? BgH$m EH$ n[aUm_ {b{IE & A brH $V S>mBH $mo_oQ> {db`Z mam Fe(II) bdU H$m Am grH$aU Xem Zo Ho$ {bE Am`{ZH$ g_rH$aU {b{IE & 14 5 5 (a) (b) Account for the following : (i) Manganese shows maximum number of oxidation states in 3d series. (ii) Eo value for Mn3+/Mn2+ couple is much more positive than that for Cr3+/Cr2+. (iii) Ti4+ is colourless whereas V4+ is coloured in an aqueous solution. Write the chemical equations for the preparation of KMnO4 from MnO2. Why does purple colour of acidified permanganate solution decolourise when it oxidises Fe2+ to Fe3+ ? OR (a) Write one difference between transition elements and p-block elements with reference to variability of oxidation states. (b) Why do transition atomization ? (c) Name an element of lanthanoid series which is well known to shown +4 oxidation state. Is it a strong oxidising agent or reducing agent ? (d) What is lanthanoid contraction ? Write its one consequence. (e) Write the ionic equation showing the oxidation of Fe(II) salt by acidified dichromate solution. 56/3/1 metals 15 exhibit higher enthalpies of P.T.O.

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