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Class 12 Maharashtra HSC 12th 2013 : Chemistry

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Target Publications Pvt. Ltd. Chemistry board question paper: march 2013 Chemistry Time: 3 Hours Total Marks: 70 Note: i. All questions are compulsory. ii. Answer to the two sections are to be written in the same answer book. iii. Figure to the right hand side indicate full marks. iv. Write balanced chemical equations and draw neat and labelled diagrams wherever necessary. v. Every new question must be started on a new page. vi. Use of logarithmic table is allowed SECTION I Q.1. Select and write the most appropriate answer from the given alternatives for each sub-question: i. In body centred cubic structure, the space occupied is about _______. (B) 53 % (A) 68 % (C) 38 % (D) 32 % ii. For a gaseous reaction, the unit of rate of reaction is _______. (B) atm mol 1 s 1 (A) L atm s 1 1 (C) atm s (D) mol s iii. Which of the following compounds contains S = O as well as S = S bonds? (A) Sulphuric acid (B) Thiosulphuric acid (C) Sulphurous acid (D) Thiosulphurous acid iv. Which of the following solutions shows maximum depression in freezing point? (A) 0.5 M Li2SO4 (B) 1 M NaCl (C) 0.5 M Al2(SO4)3 (D) 0.5 M BaCl2 v. For a chemical reaction, S = 0.035 kJ/K and H = 20 kJ. At what temperature does the reaction turn non-spontaneous? (A) 5.14 K (B) 57.14 K (C) 571.4 K (D) 5714.0 K vi. The standard e.m.f of the following cell is 0.463 V Cu | Cu++(1 M) || Ag+(1M) | Ag. If E oAg = 0.800 V, What is the standard potential of Cu electrode? (A) 1.137 V (B) (C) 0.463 V (D) vii. [7] 0.337 V 0.463 V Fe2O3 is reduced to spongy iron near the top of blast furnace by _______. (A) H2 (B) CaO (C) SiO2 (D) CO Q. 2. Answer any SIX of the following: i. Distinguish between crystalline solid and amorphous solid. [12] ii. State Kohlrausch Law and write mathematical expression of molar conductivity of the given solution at infinite dilution. iii. Write cell reactions in lead storage battery during discharge. 65 Target Publications Pvt. Ltd. Board Question Paper: March 2013 iv. Draw structures and write geometry of PCl3 and PCl5. v. Prove that H = U + nRT. What is the condition under which U = H? vi. Mention names and formulae of two ores of aluminium. vii. Derive the relationship between relative lowering of vapour pressure and molar mass of non-volatile solute. viii. What is pseudo first order reaction? Give one example of it. Q.3. Answer any THREE of the following: i. Calculate the mole fraction and molality of HNO3 in a solution containing 12.2 % HNO3. (Given atomic masses : H = 1, N = 14, O = 16) ii. Consider the reaction, 2 3I (aq) + S2 O82 I 3(aq) + 2SO 4(aq) At particular time t, d SO 24 = 2.2 10 2 M/s. dt What are the values of the following at the same time? d I d S2 O82 a. b. c. dt dt d I 3 dt iii. 300 M mol of perfect gas occupies 13 L at 320 K. Calculate the work done in joules when the gas expands a. isothermally against a constant external pressure of 0.20 atm. b. isothermal and reversible process. c. into vaccum until the volume of gas is increased by 3 L. (R = 8.314 J mol 1 K 1) iv. What is the action of the following reagents on ammonia? a. Excess of air b. Excess of chlorine c. Na metal Q. 4. Answer any ONE of the following: i. a. Explain with reason sign conventions of S in the following reactions : 1. N2(g) + 3H2(g) 2NH3(g) 2. CO2(g) CO2(s) ii. 66 [9] b. Explain the following terms: 1. Smelting 2. Flux c. Gold occurs as face centred cube and has a density of 19.30 kg dm 3. Calculate atomic radius of gold. (Molar mass of Au = 197) a. Explain the trends in the following properties with reference to group 16: 1. Atomic radii and ionic radii 2. Density 3. ionisation enthalpy 4. Electronegativity b. In the electrolysis of AgNO3 solution 0.7g of Ag is deposited after a certain period of time. Calculate the quantity of electricity required in coulomb. (Molar mass of Ag is 107.9 g mol 1). c. Define Osmosis. [7] Target Publications Pvt. Ltd. Chemistry SECTION II Q.5. Select and write the most appropriate answer from the given alternatives for each sub-question: i. In which of the following pairs, highest oxidation states of transition metals are found? (A) nitriles and chlorides (B) fluorides and chlorides (C) fluorides and oxides (D) nitriles and oxides ii. Which of the following carbocations is least stable? CH2 CH3 (A) + + CH3 CH2 C (B) CH3 CH2 CH CH2 CH3 CH2 CH3 H (C) + + (D) CH3 CH2 CH2 CH3 CH2 CH C CH3 CH3 R iii. OR C Compound having general formula H (A) (C) is called _______. OR diester hemiacetal (B) (D) acid anhydride acetal iv. The complex ion [Co(H2O)5 (ONO)]2+ and [Co(H2O)5NO2)]2+ are called _______. (A) linkage isomer (B) ionisation isomer (C) co-ordination isomer (D) geometrical isomer v. Inflammation of tongue is due to the deficiency of _______. (A) vitamin B1 (B) vitamin B2 (C) vitamin B5 (D) vitamin B6 vi. Identify the compound B in the following series of reaction: NaNO 2 Na /alc propanenitrile A B. dil.HCl (A) (C) vii. n-propyl chloride n-propyl alcohol (B) (D) Propanamine Isopropyl alcohol Which of the following reagents is best for the following conversion? O H (A) (C) LiAlH4 H2/ Ni, 453 K OH (B) (D) H3O+ Zn Hg + HCl(con) 67 [7] Target Publications Pvt. Ltd. Board Question Paper: March 2013 Q.6. Answer any SIX of the following : + i. Calculate magnetic moment of Fe 2(aq) ion (Z = 26). ii. How is ethanol prepared from methanal by using Grignard reagent? iii. Write the chemical reaction to prepare novolac polymer. iv. Why does p-nitrochlorobenzene undergo displacement reactions readily with attack of nucleophilic HO ion? v. What is the action of bromine in alkaline medium on a. CH3CH2NO2 b. CH3 CH NO2 [12] CH3 vi. Define antioxidants and mention two examples. vii. How is 4-methylpent-3-en-2-one obtained from propan-2-one? viii. What are hormones? Write the structure of simple triglycerides. Q.7. Answer any THREE of the following: i. Write the different oxidation states of manganese. Why +2 oxidation state of manganese is more stable? ii. How are the following compounds prepared? a. benzaldehyde from benzene b. acetophenone from benzene c. benzaldehyde from benzoyl chloride iii. Define complex lipids and write the structures of nucleotide and nucleoside. iv. Write the formulae of the following compounds: a. Sodium hexanitrito N cobaltate (III) b. Tetraaquodichlorochromium (III) chloride c. Potassium tetracyanoaurate (III) ion Q.8. Answer any ONE of the following: i. a. Explain the following terms: 1. Homopolymers 2. Elastomers ii. 68 b. Explain the mechanism of cleansing action of soaps. c. Write balanced chemical equations for the action of 1. phosphorus trichloride on propan-2-ol 2. hydrogen bromide on styrene in the presence of a peroxide 3. methyl bromide on silver propanoate a. Write a short note on Hoffmann bromamide degradation. b. Explain the mechanism of action of hydroiodic acid on 3-methylbutan-2-ol. c. Mention two uses of propan-2-one. [9] [7]

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