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Page 1 CBSE XII CHEMISTRY Board Paper – 2017 Solution CBSE Class XII Chemistry Board Paper 2017 (Solution) 1. The formula of an oxo-anion of manganese (Mn) in which it shows the oxidation state equal to its group number is 2 4 MnO ? . In 2 4 MnO ? , the oxidation state of Mn is Mn + (-2 × 4) = -1 Mn – 8 = -1 Mn = +7 The group number of manganese is 7. 2. The IUPAC name of the given compound is N-ethyl-N-methylethanamine. 3. The order of the given reaction is first order. The rate of reaction for the first order reaction is independent of the initial concentration of the reaction. 4. Structure of 1-bromo-4-chlorobut-2-ene: 5. One similarity between physisorption and chemisorption is that the rate of adsorption increases with an increase in the surface area of the adsorbent. 6. Completed reactions are (i) 3 2 3 NH 3Cl (excess) NCl 3HCl ? ? ?? ? ? (ii) 6 2 2 2 XeF 2H O XeO F 4HF ? ? ?? ? ? OR (i) When (NH4)2Cr2O7 is heated, it decomposes to produce Cr2O3, H2O and N2. 4 2 2 7 2 3 2 2 (NH ) Cr O Cr O 4H O N ? ? ? ? ? ? ? (ii) H2PO3 or orthophosphorous acid (or phosphorous acid) on heating dissociates to give orthophosphoric acid or phosphoric acid and phosphine. 3 3 3 4 3 4H PO 3H PO PH ? ? ? ? ? ? Page 2 CBSE XII CHEMISTRY Board Paper – 2017 Solution CBSE Class XII Chemistry Board Paper 2017 (Solution) 1. The formula of an oxo-anion of manganese (Mn) in which it shows the oxidation state equal to its group number is 2 4 MnO ? . In 2 4 MnO ? , the oxidation state of Mn is Mn + (-2 × 4) = -1 Mn – 8 = -1 Mn = +7 The group number of manganese is 7. 2. The IUPAC name of the given compound is N-ethyl-N-methylethanamine. 3. The order of the given reaction is first order. The rate of reaction for the first order reaction is independent of the initial concentration of the reaction. 4. Structure of 1-bromo-4-chlorobut-2-ene: 5. One similarity between physisorption and chemisorption is that the rate of adsorption increases with an increase in the surface area of the adsorbent. 6. Completed reactions are (i) 3 2 3 NH 3Cl (excess) NCl 3HCl ? ? ?? ? ? (ii) 6 2 2 2 XeF 2H O XeO F 4HF ? ? ?? ? ? OR (i) When (NH4)2Cr2O7 is heated, it decomposes to produce Cr2O3, H2O and N2. 4 2 2 7 2 3 2 2 (NH ) Cr O Cr O 4H O N ? ? ? ? ? ? ? (ii) H2PO3 or orthophosphorous acid (or phosphorous acid) on heating dissociates to give orthophosphoric acid or phosphoric acid and phosphine. 3 3 3 4 3 4H PO 3H PO PH ? ? ? ? ? ? CBSE XII CHEMISTRY Board Paper – 2017 Solution 7. (i) Colligative properties: Properties of solutions which depend on the number of solute particles and are independent of their chemical identity or their nature relative to the total number of particles present in the solution are called colligative properties. Examples: Lowering of vapour pressure, elevation of boiling point, depression of freezing point, osmotic pressure (ii) Molality: Molality (m) is the number of moles of the solute per kilogram (kg) of the solvent. It is expressed as Molesof soluteinkg Molality(m) Molesof solventinkg ? Example: 1.00 mol kg -1 (or 1.00 m) solution of KCl means that 1 mol (74.5 g) of KCl is dissolved in 1 kg of water. 8. (i) Structure of H2S2O7: (ii) Structure of XeF6: 9. Degree of dissociation of a weak electrolyte is given by the relation: m m m m Where, degreeof dissociationof theelectrolyte molar conducivity molar conductivity atinf inf initedilution ? ? ? ?? ?? ?? ? ? ? Page 3 CBSE XII CHEMISTRY Board Paper – 2017 Solution CBSE Class XII Chemistry Board Paper 2017 (Solution) 1. The formula of an oxo-anion of manganese (Mn) in which it shows the oxidation state equal to its group number is 2 4 MnO ? . In 2 4 MnO ? , the oxidation state of Mn is Mn + (-2 × 4) = -1 Mn – 8 = -1 Mn = +7 The group number of manganese is 7. 2. The IUPAC name of the given compound is N-ethyl-N-methylethanamine. 3. The order of the given reaction is first order. The rate of reaction for the first order reaction is independent of the initial concentration of the reaction. 4. Structure of 1-bromo-4-chlorobut-2-ene: 5. One similarity between physisorption and chemisorption is that the rate of adsorption increases with an increase in the surface area of the adsorbent. 6. Completed reactions are (i) 3 2 3 NH 3Cl (excess) NCl 3HCl ? ? ?? ? ? (ii) 6 2 2 2 XeF 2H O XeO F 4HF ? ? ?? ? ? OR (i) When (NH4)2Cr2O7 is heated, it decomposes to produce Cr2O3, H2O and N2. 4 2 2 7 2 3 2 2 (NH ) Cr O Cr O 4H O N ? ? ? ? ? ? ? (ii) H2PO3 or orthophosphorous acid (or phosphorous acid) on heating dissociates to give orthophosphoric acid or phosphoric acid and phosphine. 3 3 3 4 3 4H PO 3H PO PH ? ? ? ? ? ? CBSE XII CHEMISTRY Board Paper – 2017 Solution 7. (i) Colligative properties: Properties of solutions which depend on the number of solute particles and are independent of their chemical identity or their nature relative to the total number of particles present in the solution are called colligative properties. Examples: Lowering of vapour pressure, elevation of boiling point, depression of freezing point, osmotic pressure (ii) Molality: Molality (m) is the number of moles of the solute per kilogram (kg) of the solvent. It is expressed as Molesof soluteinkg Molality(m) Molesof solventinkg ? Example: 1.00 mol kg -1 (or 1.00 m) solution of KCl means that 1 mol (74.5 g) of KCl is dissolved in 1 kg of water. 8. (i) Structure of H2S2O7: (ii) Structure of XeF6: 9. Degree of dissociation of a weak electrolyte is given by the relation: m m m m Where, degreeof dissociationof theelectrolyte molar conducivity molar conductivity atinf inf initedilution ? ? ? ?? ?? ?? ? ? ? CBSE XII CHEMISTRY Board Paper – 2017 Solution Given 21 21 3 21 m (H ) 349.6Scm mol (CH COO ) 40.9Scm mol Molar conducvtivity( ) 39.05Scm mol ?? ?? ? ? ? ? ? ? ? ?? Hence, limiting molar conductivity of acetic acid is m3 21 acetic acid (H ) (CH COO ) 40.9 349.8 390.7cm mol ?? ? ? ? ? ? ? ? ? ? ?? ? Degree of dissociation of acetic acid, m m 39.05 390.7 0.0999 0.1 ? ? ? ?? ? ? ? Degree of dissociation of acetic acid is 0.1. 10. (i) Wolff–Kishner reduction (ii) Etard reaction Page 4 CBSE XII CHEMISTRY Board Paper – 2017 Solution CBSE Class XII Chemistry Board Paper 2017 (Solution) 1. The formula of an oxo-anion of manganese (Mn) in which it shows the oxidation state equal to its group number is 2 4 MnO ? . In 2 4 MnO ? , the oxidation state of Mn is Mn + (-2 × 4) = -1 Mn – 8 = -1 Mn = +7 The group number of manganese is 7. 2. The IUPAC name of the given compound is N-ethyl-N-methylethanamine. 3. The order of the given reaction is first order. The rate of reaction for the first order reaction is independent of the initial concentration of the reaction. 4. Structure of 1-bromo-4-chlorobut-2-ene: 5. One similarity between physisorption and chemisorption is that the rate of adsorption increases with an increase in the surface area of the adsorbent. 6. Completed reactions are (i) 3 2 3 NH 3Cl (excess) NCl 3HCl ? ? ?? ? ? (ii) 6 2 2 2 XeF 2H O XeO F 4HF ? ? ?? ? ? OR (i) When (NH4)2Cr2O7 is heated, it decomposes to produce Cr2O3, H2O and N2. 4 2 2 7 2 3 2 2 (NH ) Cr O Cr O 4H O N ? ? ? ? ? ? ? (ii) H2PO3 or orthophosphorous acid (or phosphorous acid) on heating dissociates to give orthophosphoric acid or phosphoric acid and phosphine. 3 3 3 4 3 4H PO 3H PO PH ? ? ? ? ? ? CBSE XII CHEMISTRY Board Paper – 2017 Solution 7. (i) Colligative properties: Properties of solutions which depend on the number of solute particles and are independent of their chemical identity or their nature relative to the total number of particles present in the solution are called colligative properties. Examples: Lowering of vapour pressure, elevation of boiling point, depression of freezing point, osmotic pressure (ii) Molality: Molality (m) is the number of moles of the solute per kilogram (kg) of the solvent. It is expressed as Molesof soluteinkg Molality(m) Molesof solventinkg ? Example: 1.00 mol kg -1 (or 1.00 m) solution of KCl means that 1 mol (74.5 g) of KCl is dissolved in 1 kg of water. 8. (i) Structure of H2S2O7: (ii) Structure of XeF6: 9. Degree of dissociation of a weak electrolyte is given by the relation: m m m m Where, degreeof dissociationof theelectrolyte molar conducivity molar conductivity atinf inf initedilution ? ? ? ?? ?? ?? ? ? ? CBSE XII CHEMISTRY Board Paper – 2017 Solution Given 21 21 3 21 m (H ) 349.6Scm mol (CH COO ) 40.9Scm mol Molar conducvtivity( ) 39.05Scm mol ?? ?? ? ? ? ? ? ? ? ?? Hence, limiting molar conductivity of acetic acid is m3 21 acetic acid (H ) (CH COO ) 40.9 349.8 390.7cm mol ?? ? ? ? ? ? ? ? ? ? ?? ? Degree of dissociation of acetic acid, m m 39.05 390.7 0.0999 0.1 ? ? ? ?? ? ? ? Degree of dissociation of acetic acid is 0.1. 10. (i) Wolff–Kishner reduction (ii) Etard reaction CBSE XII CHEMISTRY Board Paper – 2017 Solution 11. 12 22 11 -1 f Solution: Molarmassof sugar(C H O )=12x12+22x1+11x16 =342gmol ?T = 2 7 3 . 1 5 -2 6 9 . 1 5 =4K 10% solutionof sucrosemeans10gof canesugar ispresent =100-10=90gof water 10 No.of molesof cane sugar= 342 =029mol molalityof the solu -1 ff f -1 6 12 6 -1 0.029x1000 tion= 90 =0.324molkg Weknow, ?T = K x m 4 K= 0.324 =12.334Kkgmol Molarmassof glucose(C H O )=6x12+12x1+6x16 =180gmol 10% solutionof glucose means10gof canesugar ispresent =100-10 =90gof water Number of moles -1 ff 10 of glucose= mol=0.055mol 180 0.055x1000 Molalityof the solution= =0.616molkg 90 Usingthe relation, ?T = K x m =12.33x0.616 =7.6 Therefore,the freezing pointof10%glucose solution=273.15-7.6 =265.5K Page 5 CBSE XII CHEMISTRY Board Paper – 2017 Solution CBSE Class XII Chemistry Board Paper 2017 (Solution) 1. The formula of an oxo-anion of manganese (Mn) in which it shows the oxidation state equal to its group number is 2 4 MnO ? . In 2 4 MnO ? , the oxidation state of Mn is Mn + (-2 × 4) = -1 Mn – 8 = -1 Mn = +7 The group number of manganese is 7. 2. The IUPAC name of the given compound is N-ethyl-N-methylethanamine. 3. The order of the given reaction is first order. The rate of reaction for the first order reaction is independent of the initial concentration of the reaction. 4. Structure of 1-bromo-4-chlorobut-2-ene: 5. One similarity between physisorption and chemisorption is that the rate of adsorption increases with an increase in the surface area of the adsorbent. 6. Completed reactions are (i) 3 2 3 NH 3Cl (excess) NCl 3HCl ? ? ?? ? ? (ii) 6 2 2 2 XeF 2H O XeO F 4HF ? ? ?? ? ? OR (i) When (NH4)2Cr2O7 is heated, it decomposes to produce Cr2O3, H2O and N2. 4 2 2 7 2 3 2 2 (NH ) Cr O Cr O 4H O N ? ? ? ? ? ? ? (ii) H2PO3 or orthophosphorous acid (or phosphorous acid) on heating dissociates to give orthophosphoric acid or phosphoric acid and phosphine. 3 3 3 4 3 4H PO 3H PO PH ? ? ? ? ? ? CBSE XII CHEMISTRY Board Paper – 2017 Solution 7. (i) Colligative properties: Properties of solutions which depend on the number of solute particles and are independent of their chemical identity or their nature relative to the total number of particles present in the solution are called colligative properties. Examples: Lowering of vapour pressure, elevation of boiling point, depression of freezing point, osmotic pressure (ii) Molality: Molality (m) is the number of moles of the solute per kilogram (kg) of the solvent. It is expressed as Molesof soluteinkg Molality(m) Molesof solventinkg ? Example: 1.00 mol kg -1 (or 1.00 m) solution of KCl means that 1 mol (74.5 g) of KCl is dissolved in 1 kg of water. 8. (i) Structure of H2S2O7: (ii) Structure of XeF6: 9. Degree of dissociation of a weak electrolyte is given by the relation: m m m m Where, degreeof dissociationof theelectrolyte molar conducivity molar conductivity atinf inf initedilution ? ? ? ?? ?? ?? ? ? ? CBSE XII CHEMISTRY Board Paper – 2017 Solution Given 21 21 3 21 m (H ) 349.6Scm mol (CH COO ) 40.9Scm mol Molar conducvtivity( ) 39.05Scm mol ?? ?? ? ? ? ? ? ? ? ?? Hence, limiting molar conductivity of acetic acid is m3 21 acetic acid (H ) (CH COO ) 40.9 349.8 390.7cm mol ?? ? ? ? ? ? ? ? ? ? ?? ? Degree of dissociation of acetic acid, m m 39.05 390.7 0.0999 0.1 ? ? ? ?? ? ? ? Degree of dissociation of acetic acid is 0.1. 10. (i) Wolff–Kishner reduction (ii) Etard reaction CBSE XII CHEMISTRY Board Paper – 2017 Solution 11. 12 22 11 -1 f Solution: Molarmassof sugar(C H O )=12x12+22x1+11x16 =342gmol ?T = 2 7 3 . 1 5 -2 6 9 . 1 5 =4K 10% solutionof sucrosemeans10gof canesugar ispresent =100-10=90gof water 10 No.of molesof cane sugar= 342 =029mol molalityof the solu -1 ff f -1 6 12 6 -1 0.029x1000 tion= 90 =0.324molkg Weknow, ?T = K x m 4 K= 0.324 =12.334Kkgmol Molarmassof glucose(C H O )=6x12+12x1+6x16 =180gmol 10% solutionof glucose means10gof canesugar ispresent =100-10 =90gof water Number of moles -1 ff 10 of glucose= mol=0.055mol 180 0.055x1000 Molalityof the solution= =0.616molkg 90 Usingthe relation, ?T = K x m =12.33x0.616 =7.6 Therefore,the freezing pointof10%glucose solution=273.15-7.6 =265.5K CBSE XII CHEMISTRY Board Paper – 2017 Solution 12. (i) Solution: t = 15 min = 900 s I= 2A Molar mass of Ag = 108 gmol -1 1 F = 96500 C mol -1 Q=It Q=2 900 Q=1800 C ? From the reaction, Ag + + e - ? Ag Mass of Ag deposited QM nF 108 1800 1 96500 2.01 g ? ? ? ? ? Mass of Ag deposited is 2.01 g. (ii) A fuel cell is an electrochemical cell which converts chemical energy of a spontaneous redox reaction to electrical energy. 13. (i) Coordination isomerism (ii) In [Ni(H2O)6] 2+ , Ni 2+ ion has two unpaired electrons, and hence, it is coloured. In [Ni(CN)4] 2- , there is no unpaired electron, and hence, it is colourless. (iii) Pentaamminecarbonatocobalt(III) chloride 14. (i) Lyophilic sol Lyophobic sol Relatively stable as strong forces of interaction exist between colloidal particles and liquid. Less stable as weak forces of interaction exist between colloidal particles and liquid.Read More
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