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Class 12 ISC Prelims 2017 : Chemistry (Salt Lake School, Kolkata)

4 pages, 60 questions, 30 questions with responses, 31 total responses
Saptarshi Biswas
Salt Lake School, Kolkata
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SALT LAKE SCHOOL (English Medium) Selection Test- 2014-15 (Class- XII) CHEMISTRY Time- (15 mins reading time + 3hrs writing time) F.M-70 SECTION - I (Attempt all questions) 1.a)FiIl in the blanks with words from those given in brakets:[heterolytic, molesr-si] CH3CH2NC,homolytic, CH3CH2CN, night-blindness, beri-beri, scurvy, 1st, 2nd, 3rd, (molesl-ijis-i, S-l, i) The unit of the rate constant of a 1st order reaction is and that of a 2nd order reaction is _ ii) Br2 undergoes cleavage in presence of H202 but cleavage in presence of H20. iii) The reaction of CH3CH2Cl+ OH- -----------7 Cl-hCHzOH is a order reaction whereas the reaction (CH3)3CCl + OH- ----------7 (CH3)3COHis a order reaction. iv) KCN gives with CH3CH2Clwhere as AgCN gives _ v) Vitamin C deficiency causes and vitamin A deficiency causes _ b)Match i) [Cu(NH3)4)2+ 0) CIF3 iii) BH3 iv)[NiC14)2v) [FeF6P- a) sp-' b) tetrahedral c) dspd) octahedral e) sp-d c) Choose the correct option from the following:i) The coordination no of Na+ ion in an unit cell of NaCI is: a) 4 b) 6 c) 8 d) 12 ii) In acidic medium, 1 mole of Mn04 - accepts how many moles of electron in a redox process? a) 1 b) 3 c) 5 d) 6 iii) Which of the following gives yellow oily liquid with nitrous acid: a) Methyl amine b) Aniline c) Dimethyl amine d) Trimethylamine iv) The most acidic among them is: a) Benzoic acid b) o-hydroxy benzoic acid c)m-hydroxy benzoic acid d) p-hydroxy benzoic acid v) The most stable ion among them is: c.) b) C.H = l C"I--l- + 0-12. + do) c. ~~_) - ~ - C:. \-) J c~..1 d) Explain :i) CH3CH2CIgives CH3CH2N02with AgN02 but with KNOz gives CH3CH20NO. ii) Zn2+precipitates out at Gr IV where as Cu> precipitates out at Gr II. iii) Ethylebenzene cannot be prepared by the alkylation of Benzene. iv) Diamond is hard but Graphite is soft. v) The size of atomic radii of Zr and Hf are almost equal: /' , " (5X4)

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SECTION-II GROUPA (Answer any two questions) 02.a) A solution containing 0.7269 gm of camphor (mol. wt.-152) in 38.08 gm of acetone (b.p-56.3 C) boiled at 56.55 C. What is the molal elevation constant of the solvent and latent heat of vaporization b)Determine ammonium of acetone? the pH of a solution obtained by mixing equal volumes of 0.015 N ammonium nitrate solutions. (Kb=1.8 X 10.5) hydroxide and 0.15 N c) A solution containing 8.6 gm/L of urea was found to be isotonic with 3% solution of an organic non-volatile solute. Calculate the molecular weight of the solute. d)The solubility product of lead bromide is 1.8 X 10.5. If the salt is 70% dissociated in saturated solution, find the solubility of the salt. fee and bee ,whose unit cell edge lengths are 3.5 A and 3.0 A respectively. Calculate the ratio of densities of fee and bee. e) A metal crystallizes into two cubic structures- (5 X 2 ) 03.a) Explain- i) When hydrogen sulphide is passed through acidified solutions of both CUS04 and NiS04, only copper is precipitated as CuS. ii) ZnO is white but turns yellow when heated strongly. b) The partial pressure of CO2 in the reaction: CaC03(s)~CaO (s) + CO2(g), is 0.773 mm at 500 e. Calculate Kpfor the above reaction. ilW of the reaction is 43.2 Kcal per mole and does not change in the given range of temperature.{ R=1.98 cal.). c)What concentration d} N2 + 3H2 '" of HCOO ion is present in a solution of 0.015M HCOOH and 0.02M HCI? 2NH3; > l\H = -92 kJ. K.G\ = ,.g x 10-4 State the effect of - i} addition of reactants, ii) temperature, iii) pressure, iv) removal of product. e) 1.0 gm of strontium-90 was reduced to 0.953 gm after two years. Calculate the half life period of strontium-90. (5 X 2 ) 04.a) For the reaction, A + B -7 C + D. The activation energy of the forward and backward reactions are 85 kJjmol and 65 kJ/mol respectively. i) Calculate L'.W for the forward reaction and state the thermal nature of the reaction. ii) Prepare an activation plot. b)The time required for 10% completion of a first order reaction at 298K is equal to that required for it's 25% completion factor for the reaction is 3.56 X 109 at 308K. If the pre- exponential S l, calculate it's rate constant at 318K. (R=8.314J/K/m). c) The specific conductivity 3 of 0.02 M KCI solution at 25 C is 2.768 X 1O. 0hm \m l. The resistance of this solution in a particular cell is 250.2 ohms. The resistance of 0.01 M copper sulphate solution at 25 C, measured with the same cell was 8331 ohms. Calculate the molar conductivity of copper sulphate solution. d) Chromium metal can be plated out from an acidic solution containing Cr03, according to the following equation, Cr03 + 6H+ + 6e -7 Cr{s) + 3H20; Calculate-i) how many grams of chromium metalwill be plated out by 24000C. ii)how long will it take to plate out 1.5 g of Chromium metal, by using 12.5 ampere current? ( Cr = 52) e)i)How is molar conductivity related to the concentration ii) In the thermal decomposition of an electrolyte. Mention the equation along with the name. of C2H5Brto C2H4 and HBr, the pressure changed from an initial value of 200 mm to 390mm Hg at the end of the reaction. Show that, the fraction remained unchanged when the pressure of the mixture was 300 mm Hg is 0.47 ? (5 X 2 ) GROUPB S. a) Give the IUPAC names of the following (i) K3[Fe(C204bl (Answer any two) coordination complexes: (ii) [Cr(NH3)6][Co(CN)61 r t) '\

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b) K2[PtCI4J is ionised in aqueous solution solution? Explain your observation. c) What is matte? to give three ions. What will be the observation on adding silver nitrate (2+2+1) 6. a) Explain why among the lanthanides La(OHh is the most basic while Lu(OHh is the least basic. b) Write balanced chemical equations for the following: (i) Sulphur dioxide is passed through acidified potassium permanganate solution. (ii) Potassium dichromate is treated with acidified ferrous sulphate solution. (iii) Silver nitrate is treated with sodium thiosulphate solution. 7. a) Write the balanced equations for the extraction of silver by MacArthur-Forrest (2+3) process from argentite. b) Iodine being an electronegative element should be obtained at the anode during an electrolysis. iodine are observed at the cathode on electrolysis of molten ICI. Why? But violet vapours of c) Draw the structure of XeF6 (2+2+1) GROUP-C (Answer any two questions) Q8.a)How will you distinguish between the following pair of compounds with proper observation, reagents. i) Phenol and acetic acid. ( Using neutral FeCI3), ii) Ethyl amine and diethylamine potash soln.) iii) Formic acid and formaldehyde b) Complete and balance the following using the mentioned (chloroform and caustic (using acidified KMn04). organic reactions:- i) C6HsCHO(excess) + NaOH (conc.l-s --------- MnO ii) C6HSNH2 + CHCI3 + KOH ~ --------- iii) CH3COOH + HCOOH ~ -----573K c) Draw the structures of the isomers of the following i) 2,3-Dihydroxy butane(stereo isomer); ii) 3- Phenyl prop-2-enoic d}ldentify [AJ to [DJ with proper structure. N02,. @ A] B'r')/f"e [ " [8J 5"fV/c.lM.,HCt ) Q9.a) State the monomer units of the following i} Nylon-66, ii) Terylene, compounds, as instructed. acid (geometrical ~ND l../&~ \-tel (t>'c - s~) > [c] isomer) _C_-u._~,_t._~~ [D] (3+3+2+2) polymers. iii) PTFE. b)State your observation when glucose and fructose are separately treated with, i} Tollen's reagent, ii}bromine water. c}Define 'isoelectric point'. 'Glycine in it's dipolar ion form shows amphoteric behavior in presence of acids and bases'- explain d) Complete the following (A to F). . I)CH3COOH iii) soa')../ NH} reactions by identifying , [J' A e.,..-2.! N A-O 14 ~[~J _H,.::..'? _f' O_'2..=-------,~ [F] (3+2+2+3)

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Ql0.i)Complete ii)ldentify a) the reaction. HCHO +(KOH soln.) + ? ~ + (1+9) ? [A] to [I] with proper structures. 0 t.107,'j.'..l'U-1(lt)G'\f\,)d;J..Htt ~'2./CI+~C.(ICH (A]~)N~NO'2.at.. . ~ ~. (0' c. - 5 'c) @ ~rIJ"'" Lf? (o c - S' c) i.I..) CwBr/HB't' NH2 ~[c] LL) No..N 02./, c:i ",1..1.fCt i) [D] 0 II b) @N/'@ H (H". c) d) @-sC),l-'l @t Cc.n..(,.H NO~ 7 CC'11C. H2SO4 ~('ll.t/ (~" ~ (Fl Kt-I-\ ~(Mh04 ii,.) 14.3 (l (cIf'),(O),.(I .~ i~) 14_,04- [ ] '0 'N14:3 [~J -+ N "-0 H '7 + > C1.l C"",(.N [C:r1

 

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