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Class: Preliminary Examination -2018 You will not be allowed to write during the first 15 minutes This time is to be spent in reading the question paper. Answer all questions are compulsory Question 1 is of 20 marks having four sub parts all of which are compulsory. Question numbers 2 to 8 carry 2 marks with two questions having internal choice. Question numbers 9 to 15 carry 3 marks with two questions having internal choice. Question numbers 16 to 18 carry5 marks each. Each question has an internal choice. Some useful constants - R=0.0821 latmK-1mol-1, 8.314 JK-1mol-1 h=6.626 x 10 -34Js Me =9.1 X 10 -31 Kg, C= 3 x 108 m/s. Atomic weight: H=1, C=12, N=14, O=16, Na=23, Mg=24, Al=27, K=39, Cr=52 P=31, S=32, Cl=35.5, Ca=40, Fe=56, Cu=64, He=4, Li=7Mn=55 Atomic number:Cr=24,Cu=29, H=1, N=7, Na=11,Al=13, He=2,Li=3 Question 1 a) Fill in the blanks by choosing the words from those given in the brackets: [4] [+ 3 ,lower,atoms, acidic, positive,reduction, +4, hydrogen , basic, 8, negative, no gas, molecules ,+6, heat, sp3, carbon dioxide, ions, oxidation, - 3] i) ii) iii) iv) The crystal of graphite is made up of _______ while that of sodium chloride is made up of _______. Lithium has the highest standard ________ potential value and fluorine has highest standard _______ potential value. Oxidation state of Phosphorous in phosphine is _______ and sulphur in pyrosulphuric acid is _____ Phenol reacts with sodium metal and liberates ______ gas and on treatment with sodium bicarbonate releases ________ . b) Select the correct alternatives from the choices given : [4] i) A solution of 0.450 g of urea (mol.wt. 60) in 22.5 g of water showed 0.1700C of elevation in boiling point. The molal elevation constant of water is a) 0.510C. b) 0.950C c) 0.250C d) 2.250C ii) Which isomer of C4H9Br will produce 2-methylpropan-2-ol by treatment with aqueous KOH? a) n-butyl bromide b) Isobutyl bromide c) Tertiary-butyl bromide d) Sec-butyl bromide iii) Which among the following gives aldol condensation reaction? a) phenol b) benzophenone 1 c) butanone d) 2,2-dimethylpropanal iv) Carbon monoxide reduction process is used for the extraction of a) Copper b) Silver c) Iron d) Aluminium c) Match the following: i) Elastomers ii) Active mass iii) Purine iv) Coagulation [4] - molar concentration DNA Electrophoresis hydrogen bonds d) Answer the following questions: [8] i) Addition of 0.643 g of a compound to 50 mL of benzene (density 0.879 g/mL) lowers the freezing point from 5.510C to 5.030C.Calculate the molar mass of the compound. If Kf for benzene is 5.12 K.Kg.mol-1. ii) A metal complex having composition Cr(NH3)4Cl2Br2 has been isolated in two different forms A and B. The form A reacts with AgNO3 to give a white precipitate readily soluble in dilute aqueous ammonia, whereas B gives a yellow precipitate with AgNO3 and soluble in concentrated ammonia. a) Write the formula of A and B. b) State the type of isomerism exhibited by A and B. c) State the coordination number and oxidation state of the central metal ion in both the complexes. iii) Give reasons for the following questions. a) Transition metals have variable valency. b) Transition metals form alloys. iv) Give balanced chemical equations for the following. a) Diazotisation reaction b) Gabriel Pthalimide synthesis. Question 2 [2] -3 -1 a) What will be the initial rate of reaction if its rate constant is 10 s and the concentration of the reactant is 0.2 mol L-1? What fraction of the reactant will be converted into the products in 200 seconds? OR b) i) State any two differences between order and molecularity of a reaction. ii) What is instantaneous rate and average rate of the reaction? Question 3 a) Define Antibiotics. b) What are tranquillizers ? [2] 2 Question 4 Effect the following conversions. a) 1-bromoprane to propan-2-ol b) State and explain saytzeff rule with an example. [2] Question 5 Write the names of the monomers of the following polymers. i) Nylon-2-nylon-6 ii) Dacron iii) Bakelite iv) Natural rubber [2] Question 6 a) State the difference between globular proteins and fibrous proteins. b) What is meant by denaturation of protein? [2] Question 7 a) Effect the following conversions. i) Acetone to isopropyl chloride ii) Chlorobenzene to salicylaldehyde OR b) Give the mechanism of dehydration of ethanol Question 8 [2] [2] [2] a) If the half life period for a first order reaction is 69.3 second, what is the value of its rate constant? b) A first order reaction is completed 60% in 30 minutes at 270C. Calculate the rate constant of the reaction at 270C. Question 9 a) At 370C, the osmotic pressure of blood is 7.65 atm. How much glucose (mol.wt=180) Should be used per litre forintravenous injection that is isotonic with blood?[1 ] b) A solution of lactose containing 8.45 g of lactose in 100g of water has a vapour pressure of 4.559 mm of Hg at 00C. If the vapour pressure of pure water is 4.579 mm of Hg. Calculate the molecular weight of glucose. [1 ] OR c) A solution to be used in a hand lotion is prepared by mixing 90.0 g of water, 9.2 g of ethyl alcohol and 184 g of glycerol (C3H8O3). Calculate the mole fraction of glycerol present in it [ 1] 3 d) To 500 cm3of water, 3.0 x 10-3Kg of acetic acid is added. If 23% of acetic acid is dissociated, what will be the depression in freezing point? Kf and density of water are 1.86 K Kg mol-1 and 0.997 g cm-3, respectively. [2] Question 10 a) i) Name the crystal structure of copper metal. ii) What is the coordination number of copper in its crystalline state? [1] b) A compound is formed by two elements M and N. The element N forms ccp lattice and atoms of N occupy 1/3 rd of tetrahedral voids. What is the formula of the compound? [1] c) Niobium crystallized in a body centred cubic structure. If the density is 8.55 g cm-3, calculate atomic radius of niobium. [1] Question 11 a) Explain the following. [2] i) Alum is used for cleaning muddy water. ii) The addition of ferric hydroxide sol to arsenic sulphide sol results in the precipitation of both. b) What is gold number? [1] Question 12 a) State the hybridization, geometry and magnetic character of [Fe(CN)6]3- using VB theory. [1 ] b) What is meant by primary and secondary valency according to Werner s theory?[1] c) State the factors affecting the stability of the complex. [ ] Question 13 a) Give balanced chemical equations for the following. [2] i) Reaction between hydrogen sulphide and potassium permanganate in neutral medium. ii) Reaction between acidified potassium dichromate and oxalic acid solution. b) Why do transition elements exhibit higher enthalpies of atomization? [1] OR c) Explain the extraction of potassium dichromate from chromite ore with relevant balanced chemical equations. [2] d) What is lanthanoid contraction? Give any one consequence of it. [1] Question 14 How is silver extracted from its ore? Explain the process with relevant equations? [3] Question 15 a) Compare the basicity of primary, secondary and tertiary amine in aqueous phase with proper reasoning. [1] b) How will you effect the following conversions? [2] 4 i) ii) Aniline to cyanobenzene Nitroethane to ethylalcohol. Question 16 a) State the hybridization and draw the structure for the following compounds. i) ClF3 ii) XeO2F2 b) Give balanced chemical equations for the following. i) Reaction between copper and dil.nitric acid. ii) Reaction between sodium bisulphite and dil.sulphuricacid. c) Why fluorine gives only one oxide but chlorine gives a series of oxides? OR a) Give balanced chemical equations for the following. i) Reaction between chlorine gas and excess ammonia. ii) Reaction between ozone and potassium iodide solution. b) Give reasons for the following. i) Reducing character increases from NH3 to BiH3. ii) Noble gases form compounds only with oxygen and fluorine. iii) Perchloric acid is stronger acid than sulphuric acid. Question 17 a) Write a note on the following name reactions. i) Perkin reaction ii) Crossed aldol condensation. b) Why aldehydes and ketones undergonucleophilic addition reaction? c) Give balanced chemical equation for the following. i) Reaction between acetone and iodine in alkali. ii) Reaction between benzoic acid and nitration mixture. OR a) How will you distinguish between the following pair of compounds? i) Acetaldehyde and acetone. ii) Formic acid and acetic acid b) How will you effect the following conversions i) Ethane nitrile to propane ii) But-2-ene to acetone [2] [2] [1] [2] [3] [2] [1] [2] [2] [3] Question 18 a) A 0.04 N solution of a weak acid has a specific conductance 4.23 x 10-4 mho cm-1. The degree of dissociation of acid at this dilution is 0.0612. Calculate the equivalent conductance of weak acid at infinite dilution. [2] 5 b) A current of 4 amperes is passed through a molten solution for 45 minutes. 2.977 g of metal is deposited; calculate the charge carried by the metal cation if its atomic mass is 106.4 g mol-1. [1] c) State Faraday s second law of electrolysis. [1] d) Define equivalent conductance. [1] OR a) For the following cell representation Al / Al3+ (0.01M) // Sn2+(0.015) / Sn E0Al3+/Al =-1.66 V, E0Sn2+/Sn = 0.14V i) Write the cell equation. ii) Calculate the standard emf and emf of the cell. iii) Calculate the value ofGibb s free energy for the cell. [3] b) What is a fuel cell? Give an example of fuel cell. [1] c) State Kohlrausch s law. [1] 6
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