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PRE BOARD EXAMINATION 2018 CLASS 12 CHEMISTRY - PAPER 1 (Theory) F.M. : 70 Time : 3hrs All questions are compulsory Question 1 is of 20 marks having 4 sub parts, all of which are compulsory . Question No. 2 - 8 carry two marks each, with any 2 questions having internal choice . Question No. 9 - 15 carry 3 marks each, with any two questions having an internal choice . Question No. 16-18 carry 5 marks each, with an internal choice. Gag Const. R= 1.987cal deg 1 mo1 1 = 8.314 Jk 1 mo1 1 = 0.0821 dm 3atm K 1 mo1 1 H'atm=ldm 3atm = 101.3J, lF =96500 coulombs, Avogardro's no.= 6.023 x 1023 Question 1 , ~ Fill in the blanks by choosing the appropriate word/words from those given in the brackets : . . . i [Cannizaro's, Kolbe's, Gattermann, 2, 4, 6 - tribromophenol, Pyrene, Gammexane, 2,4,6 - tnnitrophenol, acid c, neutral,!, basic, electron pair, bond pair electron, lone pair of electron, Ammonium cyanide, Methyl cyanide, e,e..,!O(" , f 1..,,_cfN. Potassium Cyanide, aldolB -iwil:lov ~eparation of chlorobenzene from Benzene diazonium chloride and aqueous HCI is known as ............................ . reaction. ~cric acid is ..................... .. ~ e r s behave as weakly .................................... substances because of the presence of ........................... Of - e~rons on oxygen atom. JM1ienzaldehyde when treated with an alcoholic solution of ........................ forms ................................. . [1+1+ + + + =41 J9( Match the following : ~odegradable polymer (a) a - ami no acid ,(ij)Y-Giycosidic linkage (b) Sucrose @j)afsaccharide (c) Lactose (~ten ion (d) PHBV [41 (c) Complete the following statement by selecting the correct alternative from the choices given : ~ e half-life period of a l't order reaction is 20min. The time required for the concentration of the reacta nt to change from 0.16 M ~.02M is : (1) 80 min . ~ min (3) 40 min (4) 20 min ~ c e centred cubic lattice, atom(A) occupies the corner positions and atom (B) occupies the face centre positions. If one atom of (B) is missing from one of the face centred points, the formula of the compounds is: ~ 1 ) AzBs (2) A283 (3) AB2 (4) Az B ~ r a spontaneous reaction t:.G 0 and Egel! will be respectively : (1) -ve and +ve (2) +ve and -ve ~ 2 ) +ve and +ve (4)-ve and --ve ~..................... is an outer orbital complex (1) [Fe(CN) 6 ] 4 (3) [Co(NH3) 6]3+ (2) [Mn (CN) 6 ) 4 (4) [Ni(NH3)6]2+ l41 (d) Answer the following questions: ~~ hy is the freezing point depression (t:.T1) of 0.4M NaCl nearly twice that of 0.4M glucose solution? ( (ii~ Name the order of reaction which proceeds with a uniform rate throughout. .re ecific conductivity of 0.2m solution of KCI at 298 K is 0.025 Scm 1 . Calculate its molar conductivity. ~ f i n d Raoult's law for the elevation of boiling point of a solution . the IUPAC name of the complex (Cr(NH3) 4 Cl2J+ . What type of isomerism will be exhibited by it? ~ e two main points of difference between lyophilic and lyophobic solutions. l81 Question 2 (a) A a.is M aqueous solution of KCI exerts an osmotic pressure of 6.8atm. at 310 K. Calculate the degree of dissociation of KCI. ... / OR WA 10% aqueous solution of cane sugar (M.W=342) is isotonic with 1.754% aqueous solution of urea. molecular mass of urea. Hnd the l21 .J/u'estion 3 ~ t two major classes of antibiotics. ~ the role of Aspirin . l21 ., ,- 2- <hmstion 4 '-..7-. ives (B). The compoun d (B} on An aromatic organic compound (A) on heating with NH3 and Cu20 at high pressure g . d (A) again . 'th cu/HCI gives compoun t reatment with ice cold solution of NaN0 2 and HCI gives (C), whic_h.on heating WI [2] Identify the compounds (A), (B) & (C). Write the name of the reaction for the conversion of (B} to (C}. ~stionS e the names of the monomers for each of the following polymers : Dacron (Terylene) Nylon-6 [2] ,;:.~estion6 Draw the Howarth structure of Maltose showing glycosidic linkage. ~tion7 ~~w wi I you obtain the following : (Give balanced equation) (i Diphenyl from chlorobenzene ii) Benzene from phenol. OR (b) How will you obtain the following : (Give balanced equation) (i) Allisole from Phenol _ _jj. Ethyl acetate from Ethanol. ~st~on 8 Write two main differences between Schottky defect and Frenkel defect. Question 9 ~ h a t is Freundlich adsorption isotherm? Illustrate it with a graph and write its mathematical expression. ~ L-: ""t do you understand by the following: /1,.\ (i) [2] [2] (2] OR (3] Coagulation (ii) Hardy-Schulze Rule (iii) Flocculation value. '(J> Question 10 (a) What type of isomers are [Co(N H3 )sBr]S04 and [Co(NH3 ) 5 S04 )Br?. Give a c!Jemical test to distinguish between ~m. ~ [3] ~(~ Write the structures of optical isomers of the complex [Co(en) 2 C1 2 ]+ '{. J:ioestion 11 Give reason for each of the following : . [2+1=3] (a) Ni{II) compoundL.are_moce stable than P...t (ll) compounds but Ni(IV) compounds are less stable than Pt(IV) compounds. (b) Gelatin is added to ice-cream. ~~~n12 ~ L~~d sulphide has face centred cubic crystal structure. If the ~dge length of the unit cell of lead sulphide is 495pm, calculate the density of the crystal. "'- )P-t- \Vt, : Pb=207; S=32} \i9-Y__ How many Na+ and er ions are present in a unit cell of NaCl crystal? [3] \,.../ fui-estion 13 ~ Explain why: Mn 2 + is more stable than Fe 2 + towards oxid~t ion to +3 st ate (At.No. of Mn=25, Fe=26} @ ~ ansition elements usually form coloured ions. X:(iii) Zr and Hf exhibit similar properties. OR (b) Complete and balance the following chemical equat ions: (i) NaCl + Mn02 + H2S04 (ii) K2Cr201+ HCl(conc.)--+ (iii) Cli + S02 + H20 --+ [3] ~tion14 ~ ~ ~ rrange the following in the increasing order of their basic strength in gaseous phase (C2 Hs) 2 NH, C2 H 5NH2 , ( C2H s)3N, NH3 . ve a balanced chemical equation to convert ethyl amine to ethyl isocyanide. What is the product when aniline is treated with nitrous acid and hydrochloric acid at 273-278K? Write a balanced equation for it? ~ stionlS ~ How is silver extracted from its ore? Explain the process with relevant equations. [3] [S] r .--~-~~-- -- -~ ' Question 16 i (a ) (i) The specific conductance of a 0.0lM solution of acetic acid at 298 K is 1.65x 10-4 ohm- 1 cm- 1 . The molar conductance at infinite dilution of H+ton and CH 3 ion are 349.1 ohm- 1 cm 2 mo!- 1 and 1 2 1 40.9ohm- cm mol- respectively. -& , 2 !5 Calculate : (i) Molar conductance of the solution (ii) Degree of dissociation of CH3 COOH. (iii) Dissociation constant for acetic acid. [3] (ii) Calculate the e.m.f. of the following cell reaction at 298 K: Mg(s) + Cu 2 +(0.0001M) Mg 2 +(0.001M) + Cu Ege11=2.71V (b) (i) State Faraday's Second Law of electrolysis. [1] (ii) A current of 0.2A is passed in an aqueous solution of CuS04 for 1hr. Calculate the mass of copper deposited at the cathode. Cu =- G ~ 5 [3] (iii)What is standard hydrogen electrode? [1] coo- OR, ~estionl7 ~ Account for the following/ Explain why: \_(J.YSulphur and other heavier elements of group 16 exhibit oxidation state of +2, +4 & +6 but oxygen does not. -0-Yfron, cobalt, Nickel etc. are commonly used as catalyst. ~ n c cannot be regarded as a transition element. (ii) Draw the structures of the following : s(.l(XeF6 [5] ~03 OR (b) (i) Explain why: (1) BiH3 is more reducing in nature than NH3. (2) The other elements of group 15 form pentahalides but nitrogen of the same group does not form pentahalide. (3) Hydride of oxygen is less volatile than hydride of sulphur. (4) Complete and balance the following reactions(1) Cl2 + NaOH (hot cone.) (2) P +HN03 (cone.) ~stion18 ~ ( i ) Write the products of the following reactions - [SJ , (l~sCHO + NH2NH2 03 ~ H3 C00)2Ca-; (ii) r~e one chemical test each to distinguish between the following pairs of compounds - ;fiyCH2 = CH2 + q].Y Ethanal and Propanone [5] P m i c acid and Acetic acid. OR {b) (i) Write the chemical equations to illustrate the following name reactions(1) Wurtz - Fittig Reaction. (2) Hell - Vohard - Zelinsky reaction (HVZ reaction) (3) Cannizaro's Reaction (ii) Account for the following: (1) Phenols are more acidic than alcohols (2) use of aspartame is limited to cold food and drink.
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