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LILAVATIBAI PODAR SENIOR SECONDARY SCHOOL (ISC) CHEMISTRY - I PRELIMINARY EXAMINATION Std : XII Date : 06-01-20 Downloaded from TestPaperz.com Time : 3 hours Marks : 70 (Candidates are allowed additional 15 minutes for only reading the paper. They must NOT start writing during this time) All questions are compulsory om Question 1 is of twenty marks having four sub parts all of which are compulsory Question numbers 2 to 8 carry 2 marks with any two questions having internal choice Question numbers 9 to 15 carry 3 marks with any two questions having internal choice Question numbers 16 to 18 carry 5 marks each with internal choice Gas constant R = 1.987 cal deg-1 mol-1 = 8.314 J K-1 mol-1 = 0.0821 L atm K-1 mol-1 1 Faraday = 96500 C PART 1 Answer all questions [4 x1] er z .c Question 1 (a) Fill in the blanks by choosing word / words from those given in the brackets pa p (orange , copper , less , more , isotropic , buta -1,3-diene , anisotropic , vinyl cyanide , pink , colourless , mercury , green , zinc , hexamethylene diamine , formaldehyde , styrene , phenol ) _______ can displace hydrogen from mineral acids as its standard reduction potential is ______ than zero (ii) Glass is ______ where as NaCl is ________ (iii) _______ and _____ are monomers of buna S (iv) SO2 gas turns acidified K2Cr2O7 from _______ to _______ (b) Complete the following by selecting the correct alternatives from the choices given (i) Propene on reacting with HBr gives A . A on reacting with Na and dry ether gives B. Identify A and B [4x 1] a. b. c. d. ht tp s: // te st (i) 2-bromopropane , 2,3-dimethyl butane Iso-propyl bromide , n-hexane sec-propyl bromide , n-butane n-propyl bromide , neo-pentane Downloaded from TestPaperz.com This paper consist of 6 printed sides Page 1 of 6 Element A are at alternate corners and element B are at face centre. Due to some defect , 1/3 rd of B are missing from its lattice site. Formulae of the unit cell is a. A2B5 b. AB3 Downloaded from TestPaperz.com c. AB4 d. AB6 (iii) Highest osmotic pressure amongst the following solution shall be of a. 0.25 M NaCl b. 0.12 M aluminium nitrate c. 0.49 M glucose d. 0.17 M barium chloride (iv) The correct order for acidity between the following is a. Phenol > P-nitrophenol > water > ethanol b. P-nitrophenol > phenol > water > ethanol c. P-nitrophenol > phenol > ethanol > water d. Ethanol > water > phenol > P-nitrophenol Match the following (a) (b) (c) (d) .c er z (i) Copper (ii) Ether (iii) Scurvy (iv) Lyophilic colloids [4 x 1] Williamson synthesis Vitamin C Gelatin auto reduction pa p (c) om (ii) Answer the following questions (i) Explain the following with appropriate reasons a. Transition elements show variable oxidation state b. Transition elements can form complex salts [4x2] s: // te st (d) a. Write balanced equation : Acetic anhydride with aniline b. Convert the following : Acetic anhydride to formaldehyde (iii) a. At 25o C, 3.5 grams of albumin in 100 ml of water produces osmotic pressure of 0.0414 atm. What is the molecular weight of albumin ? b. Why does soda water fizz when the bottle is opened? Name the law that explains this phenomenon. (iv) a. One mole of an octahedral complex CoCl3.4NH3 gives one mole of AgCl when excess of silver nitrate is added to it. Give the IUPAC name and structure of the complex. b. Between [Fe(H2O)6]3+ and [Fe(C2O4)3]3- , which complex is more stable. Justify the answer ht tp (ii) Downloaded from TestPaperz.com Page 2 of 6 Downloaded from TestPaperz.com [2] Question 3 a. Distinguish between narrow based and broad based spectrum antibiotics b. Explain anti fertility drugs with a suitable example [2] om Question 2 a. For a reaction 2N2O5 2NO2 + O2, the rate and rate constants are 1.02 x 10-4 mol L-1 sec-1 and 3.4 x 10-5 sec-1. Calculate the molar concentration of N2O5 b. 87.5 % of first order reaction was completed in 60 minutes. Calculate the time taken for completion for half life of the reaction OR a. A substance decomposes by the following first order reaction. If 50 % of the compound is decomposed in 70 minutes. How long will it take for 70% of the compound to decompose ? er z .c Question 4 [2] An organic compound A on reacting with Cl2 and Anhydrous AlCl3 gives B. B on further reacting with NaOH at 623 k and 200 atmosphere give C. C on hydrolysis gives phenol. Identify A , B and C and mention the name reaction from B to phenol pa p Question 5 [2] a. What is the name of the polymer obtained from caprolactum? Is it an addition polymer or condensation polymer? b. Give reason : Bakelite cannot be remoulded [2] Question 7 Write balanced equations for the following i. Tert-butyl alcohol from acetone ii. Salicyldehyde from phenol [2] s: // te st Question 6 a. Distinguish between glucose and fructose with a good chemical test b. Define : Denaturation of proteins tp OR Write IUPAC names of all possible alcohols with the formulae C4H10O ht Question 8 [2] The time required for 10 % completion of a reaction of a first order reaction at 298 K is equal to that required for its 25 % completion at 308 K . if the value of A is 4 x 1010 s-1. Calculate the K at 298 K and activation energy Question 9 [3] a. Can a mixture of ethyl alcohol and water be separated completely by fractional distillation ? Justify the answer b. A solution of urea in water has a boiling point of 100.250C. Molal constants for water Kf and Kb are 1.86 K m-1 and 0.512 K m-1respectively. Calculate the depression in freezing point of the same solution c. A 4 % (W/v) solution of cane sugar is isotonic with 1% (W/v) solution of unknown compound. Find the molecular weight of unknown compound. OR Downloaded from TestPaperz.com Page 3 of 6 Downloaded from TestPaperz.com a. The osmotic pressure of 0.01 molar solution of an electrolyte is found to be 0.65 atm at 270C. Calculate the van t Hoff factor. What conclusion can you draw about the molecular state of the solute in the solution? b. What will be the value of vant s hoff factor of benzoic acid , it dimerises in aqueous solution ? what will be the experimental molecular weight vary as compared to normal molecular weight ? Justify your answer Question 10 a. Niobium crystalises in BCC structure. If density is 8.55 g/cm3 calculate atomic radius in cm of niobium using its atomic mass 93u. [3] b. Observe the diagram er z iii. om ii. Name the defect exhibited in the diagram Classify the defect as stoichiometric or non stoichiometric defect How shall this defect affect the density of the crystal .c i. [3] Question 12 a. What type of structural isomers are [Co(NH3)5Br]SO4 and [Co(NH3)5SO4]Br? Give a chemical test to distinguish the isomer. b. State the hybridization and shape of [ Ni (CO)4 ] Also mention the IUPAC name of the complex c. Name the coordinate compound used for treatment of cancer [3] tp s: // te st pa p Question 11 Explain the following with appropriate reasons a. Chemisorption increases initially with increase in temperature but decreases with more increase in temperature b. Sky is blue coloured c. Ferric chloride is preffered over potassium chloride in case of a cut leading to bleeding ht Question 13 [3] a. Answer the following i. Explain : The paramagnetic character in 3d transition series increases upto Mn and then decreases ii. Explain : CuCl salt is colourless , where as Cu(NO3)2 is blue in colour iii. State the general electronic configuration of lanthanides and its common oxidation number OR b. Complete and balance the following chemical equations. ______ + ______ + ______ + ______ i. KMnO4 + H2SO4 + FeSO4 ii. K2Cr2O7 + H2SO4 + (COOH)2 ______ + ______ + ______ + ______ Downloaded from TestPaperz.com ______ + ______ + ______ + ______ iii. KMnO4 + H2SO4 + KI Page 4 of 6 Downloaded from TestPaperz.com Question 14 a. Give reason : Gabriel phalimide reaction cannot be used for preparation of aniline b. Convert the following : ethyl alcohol to n-propyl amine c. Arrange the following in increasing order of solubility : dimethyl amine , methyl amine , aniline. Justify your answer [3] Question 15 Write chief one of zinc. How is zinc extracted from its chief ore ? An element A( at wt : 112) and B( at wt : 27) form chlorides. Solutions of these chlorides were electrolysed separately and it if found that when same amount of electricity is passed, 5.6g of A and 0.9g of B is deposited. What is the valency of A if valency of B is 3? er z .c b. [5] om Question 16 a. A solution of Ni(NO3)2 is electrolysed between platinum electrodes using a current of 5 amperes for 20min. What mass of Ni is decomposed at the cathode? [at wt of Ni= 58] pa p c. For the following cell, calculate the emf and gibb s free energy . Al / Al3+ (0.01M) | |Fe2+ (0.02M)/ Fe Given EoAl3+/Al = -1.66V and EoFe2+/Fe = -0.44V d. Define : standard hydrogen electrode te st OR a. How many electrons will flow when a current of 5 A is passed through a solution for 200s? tp s: // b. A 0.05M NH4OH solution offers the resistance of 50 ohms to a conductivity cell at 298K. If the cell constant is 0.50cm-1 and molar conductance of NH4OH at infinite dilution is 471.4 ohm-1cm2mol-1, calculate: i. Specific conductance ii. Molar conductance iii. Degree of dissociation ht c. Define : electrochemical equivalent Question 17 a. Explain why i. BiH3 is a stronger reducing agent than ammonia ii. Mixture of helium and oxygen is used in respiration by sea divers. b. i. ii. c. i. ii. Complete and balance the following chemical equations. FeSO4 + H2SO4 + Cl2 _______ + _______ H2SO4 + H2S ____ + _____ + ______ Draw the following structures Hypophosphorus acid Pyrosulphuric acid [5] Downloaded from TestPaperz.com Page 5 of 6 OR a. Explain why i. Cl can form ClF3 , but F cannot form FCl3 ii. HF is a low boiling liquid while all other Hydrogen halides are gases at room temperature. Downloaded from TestPaperz.com b. Write balanced equations for the following i. Sulphur is treated with concentrated nitric acid ii. Chlorine is treated with hot and concentrated sodium hydroxide c. State the hybridization , shape of ClF3. Support your answer with suitable diagram er z .c om Question 18 [5] a. An organic compound A has the molecular formula C7H6O. When A is treated with NaOH followed by acid hydrolysis, it gives two products, B and C. When B is oxidized, it gives A. When A and C are each separately with PCl5, they give two different organic products D and E. I Identify B to E. ii. Give the chemical reaction when A is treated with NaOH and name the reaction. pa p b. Distinguish formaldehyde and benzaldehyde with the help of a good chemical test c. Write balanced equation for the following : benzaldehyde with PCl5 st OR a. Convert the following : Phenol to benzaldoxime Downloaded from TestPaperz.com s: // te b. Write balanced equation for following name reaction i. Wolff kishner reduction ii. Perkin s reaction ht tp c. Write balance equation for the following i. Benzaldehyde with phenyl hydrazine ii. Acetone with sodium bisulphite Page 6 of 6
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