{"id":38547,"date":"2022-01-17T19:28:40","date_gmt":"2022-01-17T13:58:40","guid":{"rendered":"https:\/\/infinitylearn.com\/surge\/?p=38547"},"modified":"2022-01-21T15:13:20","modified_gmt":"2022-01-21T09:43:20","slug":"cbse-previous-year-question-papers-class-12-chemistry-2013-delhi","status":"publish","type":"post","link":"https:\/\/infinitylearn.com\/surge\/study-materials\/previous-year\/question-papers\/class-12\/chemistry-2013-delhi\/","title":{"rendered":"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_37 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" style=\"display: none;\"><label for=\"item\" aria-label=\"Table of Content\"><span style=\"display: flex;align-items: center;width: 35px;height: 30px;justify-content: center;\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/label><input type=\"checkbox\" id=\"item\"><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1' style='display:block'><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/previous-year\/question-papers\/class-12\/chemistry-2013-delhi\/#Time_allowed_3_hours_Maximum_Marks_70\" title=\"Time allowed: 3 hours \nMaximum Marks: 70\">Time allowed: 3 hours \nMaximum Marks: 70<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/previous-year\/question-papers\/class-12\/chemistry-2013-delhi\/#CBSE_Previous_Year_Question_Papers_Class_12_Chemistry_2013_Delhi_Set_I\" title=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I\">CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/previous-year\/question-papers\/class-12\/chemistry-2013-delhi\/#CBSE_Previous_Year_Question_Papers_Class_12_Chemistry_2013_Delhi_Set_II\" title=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set II\">CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set II<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/infinitylearn.com\/surge\/study-materials\/previous-year\/question-papers\/class-12\/chemistry-2013-delhi\/#CBSE_Previous_Year_Question_Papers_Class_12_Chemistry_2013_Delhi_Set_III\" title=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set III\">CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set III<\/a><\/li><\/ul><\/nav><\/div>\n<h3><span class=\"ez-toc-section\" id=\"Time_allowed_3_hours_Maximum_Marks_70\"><\/span>Time allowed: 3 hours<br \/>\nMaximum Marks: 70<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<h3><span class=\"ez-toc-section\" id=\"CBSE_Previous_Year_Question_Papers_Class_12_Chemistry_2013_Delhi_Set_I\"><\/span>CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Question 1.<br \/>\nHow many atoms constitute one unit cell of a face-centred cubic crystal? [1]\n<p>Question 2.<br \/>\nName the method used for refining of Nickel metal. [1]\nAnswer:<br \/>\nThe method used for refining of nickel metal is Mond\u2019s process.<\/p>\n<p>Question 3.<br \/>\nWhat is the covalency of nitrogen in N<sub>2<\/sub>O<sub>5<\/sub>? [1]\n<p>Question 4.<br \/>\nWrite the IUPAC name of: [1]\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574118822_4a8c39d36f_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q4\" width=\"233\" height=\"62\" \/><br \/>\nAnswer:<br \/>\n4-chloropent-1-ene.<\/p>\n<p>Question 5.<br \/>\nWhat happens when CH3Br is treated with KCN? [1]\nAnswer:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573969246_524b783598_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q5\" width=\"277\" height=\"64\" \/><br \/>\nIt is a nucleophilic substitution reaction.<\/p>\n<p>Question 6.<br \/>\nWrite the structure of 3-methyl butanal. [1]\nAnswer:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574118957_6ea2cc655d_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q6\" width=\"207\" height=\"60\" \/><\/p>\n<p>Question 7.<br \/>\nArrange the following in increasing order of their basic strength in aqueous solution:<br \/>\nCH<sub>3<\/sub>NH<sub>2<\/sub>, (CH<sub>3<\/sub>)<sub>3<\/sub>N, (CH<sub>3<\/sub>)<sub>2<\/sub>NH. [1]\nAnswer:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573969461_993db14b6b_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q7\" width=\"270\" height=\"51\" \/><\/p>\n<p>Question 8.<br \/>\nWhat are the types of an RNA molecule which perform different functions? [1]\nAnswer:<br \/>\nThree types of RNA molecules which perform different functions are:<\/p>\n<ul>\n<li>Messenger RNA (m-RNA)<\/li>\n<li>Transfer RNA (t-RNA)<\/li>\n<li>Ribosomal RNA (r-RNA)<\/li>\n<\/ul>\n<p>Question 9.<br \/>\n18 g of glucose, C<sub>6<\/sub>H<sub>12<\/sub>O<sub>6<\/sub> (Molar Mass = 180g\/ mol) is dissolved in 1 kg of water in a saucepan. At what temperature will this solution boil? [2] (K<sub>b<\/sub> for water = 0.52 K kg mol<sup>-1<\/sup>, boiling point of pure water = 373.15 K)<br \/>\nAnswer:<br \/>\nGiven,<br \/>\nWeight of solvent (H<sub>2<\/sub>O) (W<sub>1<\/sub>) = 1 kg<br \/>\nWeight of solute (C<sub>6<\/sub>H<sub>12<\/sub>O<sub>6<\/sub>) (W<sub>2<\/sub>) = 18 gm<br \/>\nMolar mass of solute (M<sub>2<\/sub>) = 180 g\/mol<br \/>\nK<sub>b<\/sub> = 0.52 K kg mol<sup>-1<\/sup><br \/>\nT<sup>0<\/sup><sub>b<\/sub> = 373.15 K<br \/>\nWe know that<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573969531_85183e120d_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q9\" width=\"200\" height=\"211\" \/><br \/>\nHence, the boiling point of a solution is 373.202 K<\/p>\n<p>Question 10.<br \/>\nThe conductivity of 0.20 M solution of KCl at 298 K is 0.025 S cm<sup>-1<\/sup>. Calculate its molar conductivity. [2]\nAnswer:<br \/>\nGiven k = 0.025 S cm<sup>-1<\/sup><br \/>\nMolarity, M = 0.20 M<br \/>\nMolar conductivity<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574119052_00dc712c5e_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q10\" width=\"194\" height=\"122\" \/><\/p>\n<p>Question 11.<br \/>\nWrite the dispersed phase and dispersion medium of the following colloidal system: [2]\n(i) Smoke<br \/>\n(ii) Milk.<br \/>\nOR<br \/>\nWhat are lyophilic and lyophobic colloids? Which of these sols can be easily coagulated on the addition of small amounts of electrolytes?<br \/>\nAnswer:<br \/>\n(i) Dispersed Phase in Smoke: Solid<br \/>\nDispersion medium in smoke: Gas<br \/>\n(ii) Dispersed Phase in Milk: Fats (liquid)<br \/>\nDispersion medium in milk: Water (liquid)<br \/>\nOR<br \/>\nLyophilic Colloids: These are the colloidal solutions in which the dispersed phase has a great affinity for the dispersion medium. Such solutions are quite stable and are reversible in nature, e.g. starch, proteins, etc.<\/p>\n<p>Lyophobic Colloids (Liquid Hating): These are the colloidal solutions in which dispersed phase has very little affinity for the dispersion medium. Such solutions are unstable and are irreversible in nature, eg., (AS<sub>2<\/sub>S<sub>3<\/sub> Sol).<\/p>\n<p>Lyophobic colloids can be easily coagulated because, on the addition of the small amount of electrolyte, the charge on colloidal particles is removed, as a result, the particles will come closer to each other and then aggregate to form a cluster which settles down under the force of gravity.<\/p>\n<p>Question 12.<br \/>\nWrite the differences between physisorption and chemisorption with respect to the following: [2]\n(i) Specificity<br \/>\n(ii) Temperature dependence<br \/>\n(iii) Reversibility and<br \/>\n(iv) Enthalpy change Answer:<br \/>\nAnswer:<\/p>\n<table border=\"2\">\n<tbody>\n<tr>\n<td width=\"32\">\n<p style=\"text-align: center\"><strong>S.No.<\/strong><\/p>\n<\/td>\n<td style=\"text-align: center\" width=\"74\"><strong>Point of difference<\/strong><\/td>\n<td style=\"text-align: center\" width=\"103\"><strong>Physisorption<\/strong><\/td>\n<td style=\"text-align: center\" width=\"103\"><strong>Chemisorption<\/strong><\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center\" width=\"32\">(i)<\/td>\n<td width=\"74\">Specificity<\/td>\n<td width=\"103\">It is not specific in nature i.e., all gases are adsorbed on all solids to some extent.<\/td>\n<td width=\"103\">This is highly specific in nature. i.e., it occurs only when there is some possibility of compound formation between the gas being adsorbed and the solid being adsorbent.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center\" width=\"32\">(ii)<\/td>\n<td width=\"74\">Tempera\u00adture dependence<\/td>\n<td width=\"103\">Low tem\u00adperature is favourable for physisorption. It decreases with increase in temperature<\/td>\n<td width=\"103\">High temperature is favourable for chemisorptions. It increases with the increase in temperature.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center\" width=\"32\">(iii)<\/td>\n<td width=\"74\">Reversi\u00adbility<\/td>\n<td width=\"103\">It is reversible in nature.<\/td>\n<td width=\"103\">It is irreversible in nature.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center\" width=\"32\">(iv)<\/td>\n<td width=\"74\">Enthalpy change<\/td>\n<td width=\"103\">Enthalpy of adsorption is low i.e., 20-40 kJ mol<sup>-1<\/sup><\/td>\n<td width=\"103\">Enthalpy of adsorption is high i.e., 40\u00ad4000 kJ mol<sup>-1<\/sup><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Question 13.<br \/>\n(a) Which solution is used for the leaching of Silver metal in the presence of air in the metallurgy of silver?<br \/>\n(b) Out of \u2018C\u2019 and \u2018CO\u2019, which is a better reducing agent at the lower temperature range in the blast furnace to extract iron from the oxide ore? [2]\nAnswer:<br \/>\n(a) Dilute solution i.e., 0.5% NaCN and KCN is used for leaching of silver metal in the presence of air.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574119142_ba1d838e29_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q13\" width=\"422\" height=\"75\" \/><br \/>\n(b) Out of C and CO, CO is a better reducing agent at a lower temperature range in the blast furnace to extract iron from the oxide ore because in Ellingham diagram \u0394G(CO, CO<sub>2<\/sub>) &lt; \u0394G(Fe, FeO) SO, CO will reduce FeO to Fe and will be oxidized to CO<sub>2<\/sub>.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573969716_c1e2249d87_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q13.1\" width=\"206\" height=\"39\" \/><\/p>\n<p>Question 14.<br \/>\nWhat happens when [2]\n(i) PCl<sub>5<\/sub> is heated?<br \/>\n(ii) H<sub>3<\/sub>PO<sub>3<\/sub> is heated?<br \/>\nWrite the reaction involved.<br \/>\nAnswer:<br \/>\n(i) PCl<sub>5<\/sub> on heating gives PCl<sub>3<\/sub> and Cl<sub>2<\/sub>.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574119377_dda2dd2b2b_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q14\" width=\"162\" height=\"42\" \/><br \/>\n(ii) H<sub>3<\/sub>PO<sub>3<\/sub> on heating gives orthophosphoric acid and phosphine.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574119462_de72f57976_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q14.1\" width=\"265\" height=\"64\" \/><\/p>\n<p>Question 15.<br \/>\n(a) Which metal in the first transition series (3d series) exhibits +1 oxidation state most frequently and why?<br \/>\n(b) Which of the following cations are coloured in aqueous solutions and why? [2]\nSc<sup>3+<\/sup>, V<sup>3+<\/sup>, Ti<sup>4+<\/sup>, Mn<sup>2+<\/sup><br \/>\n(Atomic Nos. Sc = 21, V = 23, Ti = 22, Mn = 25)<br \/>\nAnswer:<br \/>\n(a) Cu is the only metal in the first transition series (3d series) which exhibits +1 oxidation state more frequently. This is because the electronic configuration of Cu is 3d<sup>10<\/sup> 4s<sup>1<\/sup> and after losing ones electron it acquires a stable 3d<sup>10<\/sup> configuration.<\/p>\n<p>(b) The colour of cations depends upon the number of impaired electrons present in d-orbital. The electronic configuration of the following cations is as follows:<br \/>\nSc (Atomic number 21) = 3d<sup>1<\/sup>4s<sup>2<\/sup> and Sc<sup>3+<\/sup> = 3d<sup>0<\/sup>4s<sup>0<\/sup>.<br \/>\nAs d-orbital is empty, it is colourless.<br \/>\nV (atomic number 23) = 3d<sup>3<\/sup>4s<sup>2<\/sup> and V<sup>3+<\/sup> = 3d<sup>2<\/sup>4s<sup>0<\/sup>.<br \/>\nAs d-orbital is having 2 impaired electrons, it undergoes d-d transition and depicts green colour.<br \/>\nTi (Atomic number 22) = 3d<sup>2<\/sup>4s<sup>2<\/sup> and Ti<sup>4+<\/sup> = 3d<sup>0<\/sup>4s<sup>0<\/sup>.<br \/>\nAs \u2018d\u2019 orbital is empty, it is colourless.<br \/>\nMn(Atomic Number 25) = 3d<sup>5<\/sup>4s<sup>2<\/sup> and Mn<sup>2+<\/sup> = 3d<sup>5<\/sup>4s<sup>0<\/sup>.<br \/>\nAs \u2018d\u2019 orbital has 5 unpaired electrons, it depicts a pink colour.<br \/>\nThus, V<sup>3+<\/sup> and Mn<sup>2+<\/sup> ions are coloured in their aqueous solution due to the presence of impaired electron.<\/p>\n<p>Question 16.<br \/>\nChlorobenzene is extremely less reactive towards a nucleophilic substitution reaction. Give two reasons for the same. [2]\nAnswer:<br \/>\nChlorobenzene is extremely less reactive towards a nucleophilic substitution reaction because of the following reasons:<br \/>\n1. Resonance Effect: The electron pair on chlorine atom is in conjugation with the benzene electrons of the benzene ring which results in the following resonating structures:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573970066_6fe6ce1e47_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q16\" width=\"350\" height=\"266\" \/><br \/>\nThis results in delocalization of electrons of C-Cl bond and a partial double bond character develops in the bond, which makes it difficult for the nucleophile to cleave the C-Cl bond.<\/p>\n<p>2. The nucleophile suffers repulsion from the increased electron density on the benzene ring, as a result, the nucleophile is unable to make a close approach for the attack on the molecule.<\/p>\n<p>Question 17.<br \/>\nExplain the mechanism of the following reaction: [2]\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573970161_56a48fc4e1_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q17\" width=\"407\" height=\"75\" \/><br \/>\nAnswer:<br \/>\nThe mechanism of the reaction is given below:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574119732_2b036d3c8a_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q17.1\" width=\"414\" height=\"404\" \/><br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573970201_79167786fa_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q17.2\" width=\"408\" height=\"140\" \/><\/p>\n<p>Question 18.<br \/>\nHow will you convert:<br \/>\n(i) Propene to Propan-2-ol?<br \/>\n(ii) Phenol to 2, 4, 6 \u2013 trinitrophenol?<br \/>\nAnswer:<br \/>\n(i) When H<sub>2<\/sub>SO<sub>4<\/sub> is added to propene, propan-2-ol is formed. The addition of H<sub>2<\/sub>SO<sub>4<\/sub> takes place in accordance with Markovnikov\u2019s rule.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573970291_4fb18a1490_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q18\" width=\"347\" height=\"177\" \/><br \/>\n(ii) When concentrated nitric acid is added to phenol in the presence of sulphuric acid it gives 2, 4, 6 \u2013 trinitrophenol.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573970336_257a56c9df_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q18.1\" width=\"407\" height=\"182\" \/><\/p>\n<p>Question 19.<br \/>\n(a) What type of semiconductor is obtained when silicon is doped with boron? [3]\n(b) What type of magnetism is shown in the following alignment of magnetic moments?<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574119997_4afce8dd57_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q19\" width=\"116\" height=\"64\" \/><br \/>\n(c) What type of point defect is produced when AgCl is doped with CdCl<sub>2<\/sub>?<\/p>\n<p>Question 20.<br \/>\nDetermine the osmotic pressure of a solution prepared by dissolving 2.5 \u00d7 10<sup>-2<\/sup> g of K<sub>2<\/sub>SO<sub>4<\/sub> in 2 L of water at 25\u00b0C, assuming that it is completely dissociated. [3]\n(R = 0.0821 L atm K<sup>-1<\/sup> mol<sup>-1<\/sup>, Molar mass of K<sub>2<\/sub>SO<sub>4<\/sub> = 174 g mol<sup>-1<\/sup>)<br \/>\nAnswer:<br \/>\nWe know<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574119977_37fdfbeafc_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q20\" width=\"367\" height=\"277\" \/><\/p>\n<p>Question 21.<br \/>\nCalculate the emf of the following cell at 298 K: [3]\nFe(s) | Fe<sup>2+<\/sup> (0.001 M) || H<sup>+<\/sup>(1M) | H<sub>2<\/sub>(g) (1 bar), Pt(s)<br \/>\n(Given E<sup>0<\/sup><sub>cell<\/sub> = +0.44 V)<br \/>\nAnswer:<br \/>\nAt anode : Fe \u2192 Fe<sup>2+<\/sup> + 2e<sup>\u2013<\/sup><br \/>\nAt cathode: 2H<sup>+<\/sup> + 2e<sup>\u2013<\/sup> \u2192 H<sub>2<\/sub><br \/>\nSo, total number of electrons (n) transferred = 2<br \/>\nGiven that: E<sup>0<\/sup><sub>cell<\/sub> = +0.44 V<br \/>\nTemperature (T) = 298 K<br \/>\nWe know,<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120062_65b701b39b_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q21\" width=\"312\" height=\"237\" \/><\/p>\n<p>Question 22.<br \/>\nHow would you account for the following? [3]\n(i) Transition metals exhibit variable oxidation states.<br \/>\n(ii) Zr (Z = 40) and Hf (Z = 72) have almost identical radii.<br \/>\n(iii) Transition metals and their compounds act as a catalyst.<br \/>\nOR<br \/>\nComplete the following chemical equations:<br \/>\n(i) Cr<sub>2<\/sub>O<sup>2-<\/sup><sub>7<\/sub> + 6Fe<sup>2+<\/sup> + 14H<sup>+<\/sup> \u2192<br \/>\n(ii) 2CrO4<sup>\u2013<\/sup>+ 2H<sup>+<\/sup> \u2192<br \/>\n(iii) 2MnO<sup>\u2013<\/sup><sub>4<\/sub> + 5C<sub>2<\/sub>O<sup>-2<\/sup><sub>4<\/sub> + 16H<sup>+<\/sup> \u2192<br \/>\nAnswer:<br \/>\n(i) The variable oxidation states of transition elements are due to the participation of ns and (n \u2013 1)d-electrons in bonding. Lower oxidation state is exhibited when ns-electrons take part in bonding. Higher oxidation states are exhibited when (n \u2013 1) d-electrons take part in bonding.<\/p>\n<p>(ii) This is because the atomic radii of 4d and 5d transition elements are nearly the same. This similarity in size is a consequence of lanthanide contraction which is due to weak shielding of d-electrons. As a result, the radii of Hf becomes nearly equal to that of Zr.<\/p>\n<p>(iii) The catalytic activity of transition elements and their compound is due to the following reasons:<br \/>\n1. Due to their tendency to show variable oxidation state transition metal form unstable intermediate compounds and provides a new path for the reaction with lower activation energy.<br \/>\n2. In some cases, the transition metals provide a suitably large surface area with free valencies or ion which reactant can adsorb.<br \/>\nOR<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573970546_4866306547_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q22\" width=\"375\" height=\"149\" \/><\/p>\n<p>Question 23.<br \/>\nWrite the IUPAC names of the following coordination compounds: [3]\n(i) [Cr(NH<sub>3<\/sub>)<sub>3<\/sub>Cl<sub>3<\/sub>]\n(ii) K<sub>3<\/sub>[Fe(CN)<sub>6<\/sub>]\n(iii) [CoBr<sub>2<\/sub>(en)<sub>2<\/sub>]<sup>+<\/sup>, (en = ethylenediamine)<br \/>\nAnswer:<br \/>\n(i) Triamminetrichlorochromium(III)<br \/>\n(ii) Potassium hexacyanoferrate(III)<br \/>\n(iii) Dibromobis-(ethylenediamine) cobalt (III) ion<\/p>\n<p>Question 24.<br \/>\nGive the structures of A, B and C in the following reactions: [3]\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120127_e47ca6cd21_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q24\" width=\"408\" height=\"148\" \/><br \/>\nAnswer:<br \/>\n(i)<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120202_3ec62d9c28_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q24.1\" width=\"335\" height=\"483\" \/><\/p>\n<p>Question 25.<br \/>\nWrite the names and structures of the monomers of the following polymers: [3]\n(i) Buna-S<br \/>\n(ii) Neoprene<br \/>\n(iii) Nylon-6, 6<br \/>\nAnswer:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573970796_6699c56350_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q25\" width=\"404\" height=\"329\" \/><\/p>\n<p>Question 26.<br \/>\nAfter watching a programme on TV about the adverse effects of junk food and soft drinks on the health of school children, Sonali, a student of Class XII, discussed the issue with the principal. The principal immediately instructed the canteen contractor to replace the fast food with the fibre and vitamins rich food like sprouts, salad, fruits etc. This decision was welcomed by the parents and the students. [3]\nAfter reading the above passage, answer the following questions:<br \/>\n(a) What values are expressed by Sonali and the Principal of the school?<br \/>\n(b) Give two examples of water-soluble vitamins.<br \/>\nAnswer:<br \/>\n(b) The two water-soluble vitamins are vitamin B and Vitamin C (Ascorbic acid).<\/p>\n<p>Question 27.<\/p>\n<ol>\n<li>Which one of the following is a food preservative? [3]\nEquanil, Morphine, Sodium benzoate<\/li>\n<li>Why is bithional added to soap?<\/li>\n<li>Which class of drugs is used in sleeping pills?<\/li>\n<\/ol>\n<p>Answer:<\/p>\n<ol>\n<li>Sodium benzoate is used as a food preservative whereas equanil is a tranquiliser and morphine is a narcotic analgesic.<\/li>\n<li>Bithional is an antiseptic so it is added to soaps to reduce the odours produced by bacterial decomposition of organic matter on the skin.<\/li>\n<li>Tranquilisers relieve stress, fatigue by inducing a sense of well being, so they are used in sleeping pills.<\/li>\n<\/ol>\n<p>Question 28.<br \/>\n(a) A reaction is second order in A and first order in B. [5]\n(i) Write the differential rate equation.<br \/>\n(ii) How is the rate affected increasing the concentration of A three times?<br \/>\n(iii) How is the rate affected when the concentrations of both A and B are doubled?<br \/>\n(b) A first-order reaction takes 40 minutes for 30% decomposition. Calculate t<sub>1\/2<\/sub> for this reaction.<br \/>\n(Given: log 1.428 = 0.1548)<br \/>\nOR<br \/>\n(a) For a first-order reaction, show that time required for 99% completion is twice the time required for the completion of 90% of the reaction.<br \/>\n(b) Rate constant \u2018k\u2019 of a reaction varies with temperature \u2018T\u2019 according to the equation:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120237_753591697f_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q28\" width=\"215\" height=\"64\" \/><br \/>\nWhere E<sub>a<\/sub> is the activation energy. When a graph is plotted for log k Vs. \\(\\frac { 1 }{ T }\\), a straight line with a slope of -4250 K is obtained. Calculate \u2018E<sub>a<\/sub>\u2018 for the reaction. (R = 8.314 JK<sup>-1<\/sup> mol<sup>-1<\/sup>)<br \/>\nAnswer:<br \/>\n(a) (i) A reaction is second order in A and first order in B.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120287_f7f47b90ff_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q28.1\" width=\"192\" height=\"54\" \/><br \/>\n(ii) On increasing the concentration of \u2018A\u2019 three times i.e. 3A; the rate of reaction becomes 9 times the initial rate.<br \/>\nRate = K[3A]<sup>2<\/sup>[B] = 9K[A]<sup>2<\/sup>[B] = 9 times rate.<br \/>\n(iii) On increasing the concentration of A and B as 2A and 2B. The rate of reaction becomes 8 times the initial rate.<br \/>\nRate = K[2A]<sup>2<\/sup>[2B] = 8K[A]<sup>2<\/sup>[B] = 8 times rate<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120312_9b04534964_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q28.2\" width=\"146\" height=\"74\" \/><br \/>\nNow, it takes 40 min for 30% decomposition i.e. reactant left after 40 min is 70% of its initial concentration.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573970881_9a41e28fdb_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q28.3\" width=\"207\" height=\"345\" \/><br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573970931_971d25d28e_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q28.4\" width=\"373\" height=\"288\" \/><br \/>\nthe time required for 99% completion of 1st order reaction is twice the time required for 90% completion.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120437_6e900a681c_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q28.5\" width=\"343\" height=\"66\" \/><br \/>\nThe above equation is like y = mx + c, where if we plot \u2018y\u2019 vs \u2018x\u2019 we get a straight line with slope \u2018m\u2019 and intercept \u2018c\u2019.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120507_40c0e734bc_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q28.6\" width=\"319\" height=\"449\" \/><\/p>\n<p>Question 29.<br \/>\n(a) Give reasons for the following: [5]\n(i) Bond enthalpy of F<sub>2<\/sub> is lower than that of Cl<sub>2<\/sub>.<br \/>\n(ii) PH<sub>3<\/sub> has a lower boiling point than NH<sub>3<\/sub>.<br \/>\n(b) Draw the structures of the following molecules:<br \/>\n(i) BrF<sub>3<\/sub><br \/>\n(ii) (HPO<sub>3<\/sub>)<sub>3<\/sub><br \/>\n(iii)XeF<sub>4<\/sub><br \/>\nOR<br \/>\n(a) Account for the following:<br \/>\n(i) Helium is used in diving apparatus.<br \/>\n(ii) Fluorine does not exhibit a positive oxidation state.<br \/>\n(iii) Oxygen shows catenation behaviour less than sulphur.<br \/>\n(b) Draw the structures of the following molecules.<br \/>\n(i) XeF<sub>2<\/sub><br \/>\n(ii) H<sub>2<\/sub>S<sub>2<\/sub>O<sub>8<\/sub><br \/>\nAnswer:<br \/>\n(a) (i) Bond enthalpy of F<sub>2<\/sub> is lower than that of Cl<sub>2<\/sub> because \u2018F\u2019 atom is small in size and due to this the electron-electron repulsions between the lone pairs of F-F electrons are very large. Thus, the bond dissociation energy of F<sub>2<\/sub> is lower than that of Cl<sub>2<\/sub>.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120567_8ca248bd99_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q29\" width=\"273\" height=\"436\" \/><br \/>\nOR<br \/>\n(a) (i) Helium mixed with oxygen under pressure is given to sea-divers for artificial respiration because of its very low solubility in blood. Air is not given because nitrogen present in air being soluble in blood will give a painful sensation called bends by bubbling out blood on moving from high pressure to the atmospheric pressure. Thus, the oxygen-helium mixture is used.<\/p>\n<p>(ii) Fluorine being the most electronegative atom does not exhibit positive oxidation state because, it does not have d-orbitals for octet expansion and therefore, it shows only a negative oxidation state of -1.<\/p>\n<p>(iii) Oxygen shows catenation behaviour less than sulphur because the oxygen atom is smaller in size as compared to sulphur due to this the lone pair of an electron in 0-0 bonds in oxygen experiences more repulsion as compared to the S-S bonds and thus, S-S forms a strong bond.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971091_a95bf9f121_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q29.1\" width=\"293\" height=\"343\" \/><\/p>\n<p>Question 30.<br \/>\n(a) Although phenoxide ion has a number of resonating structures than carboxylate ion, the carboxylic acid is a stronger acid than phenol. Give two reasons. [5]\n(b) How will you bring about the following conversions?<br \/>\n(i) Propanone to propane<br \/>\n(ii) Benzoyl chloride to benzaldehyde<br \/>\n(iii) Ethanal to but-2-enal.<br \/>\nOR<br \/>\n(a) Complete the following reactions:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120612_16d20be710_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q30\" width=\"277\" height=\"185\" \/><br \/>\n(b) Give simple chemical tests to distinguish between the following pairs of compounds:<br \/>\n(i) Ethanal and Propanal<br \/>\n(ii) Benzoic acid and Phenol.<br \/>\nAnswer:<br \/>\n(a) On losing a proton, carboxylic acids form carboxylate ion and phenol forms phenoxide ion as follows:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971171_9c5de030e8_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q30.1\" width=\"326\" height=\"173\" \/><br \/>\nNow, the negative charge is delocalized in both molecules as follows:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120677_3f0ae3dc36_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q30.2\" width=\"279\" height=\"120\" \/><br \/>\nThe conjugate base of carboxylic acid has two resonance structures in which negative charge is delocalized over two oxygen atoms which stabilize the carboxylate ion.<\/p>\n<p>On the other hand, in phenoxide ion the charge is delocalized over the entire molecule on the less electronegative atom, thus resonance of phenoxides is not important in comparison to resonance in carboxylate ion.<br \/>\nFurther, in carboxylate ion, the negative charge is effectively delocalized over two oxygen atoms whereas it is less effectively delocalized over one oxygen atom and a less electronegative carbon atom.<br \/>\nThus, phenol is less acidic than carboxylic acids. In other words, carboxylic acids are stronger acids than phenol.<\/p>\n<p>(b) (i) Conversion of propanone to propane:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120752_195573d57a_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q30.3\" width=\"367\" height=\"213\" \/><br \/>\n(ii) Conversion of benzoyl chloride to benzaldehyde:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971276_feb00e26ac_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q30.4\" width=\"284\" height=\"171\" \/><br \/>\n(iii) On treatment with dilute alkali, ethanol produces 3-hydroxybutanal gives But-2-enal on heating<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971361_96cf0f67b8_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q30.5\" width=\"412\" height=\"552\" \/><br \/>\n(b) (i) Ethanol and Propanal:<br \/>\nIodoform Test: When ethanol is treated with sodium hydroxide and ammonia, iodoform is obtained.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971341_1b3c82b471_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q30.6\" width=\"380\" height=\"159\" \/><br \/>\n(ii) Benzoic acid and phenol:<br \/>\nNaHCO<sub>3<\/sub> Test: When benzoic acid is treated with NaHCO<sub>3<\/sub> brisk effervescence of CO<sub>2<\/sub> gas was evolved.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971366_72817f3cf6_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Q30.7\" width=\"404\" height=\"186\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"CBSE_Previous_Year_Question_Papers_Class_12_Chemistry_2013_Delhi_Set_II\"><\/span>CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set II<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Note: Except for the following questions, all the remaining questions have been asked in the previous set.<\/p>\n<p>Question 1.<br \/>\nWhat type of stoichiometric defect is shown by AgCl? [1]\n<p>Question 2.<br \/>\nWrite the IUPAC name of [1]\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574120962_769c7ceb64_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set II Q2\" width=\"203\" height=\"98\" \/><br \/>\nAnswer:<br \/>\n4-Bromo-4-methylpent-2-ene<\/p>\n<p>Question 4.<br \/>\nWhat type of bonding helps in stabilizing the a-helix structure of proteins? [1]\nAnswer:<br \/>\nHydrogen bonding between the NH group of each amino acid residue and the &gt;C = O of an adjacent turn of the helix helps in stabilizing the \u03b1-helix structure of proteins.<\/p>\n<p>Question 6.<br \/>\nWhat inspired N.Bartlett for carrying out a reaction between Xe and PtF<sub>6<\/sub>? [1]\nAnswer:<br \/>\nN.Bartlett observed that the first ionization enthalpy of molecular oxygen is almost identical to that of xenon. So after preparing red coloured compound O<sub><span style=\"font-size: 13.3333px\">2PtF6<\/span>2<\/sub> he made efforts to prepare Xe<sup>+<\/sup>PtF<sup>\u2013<\/sup><sub>6<\/sub> by mixing PtF<sub>6<\/sub> and Xe.<\/p>\n<p>Question 7.<br \/>\nWhat happens when ethyl chloride is treated with aqueous KOH? [1]\nAnswer:<br \/>\nWhen C<sub>2<\/sub>H<sub>5<\/sub>Cl reacts with aq. KOH, substitution Nucleophilic bimolecular (S<sub>N<\/sub>2) reaction takes place and Ethanol is formed.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971426_53444bc412_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set II Q7\" width=\"386\" height=\"151\" \/><br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971481_e645cd28cc_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set II Q7.1\" width=\"180\" height=\"152\" \/><br \/>\nAnd inversion of configuration also takes place.<\/p>\n<p>Question 8.<br \/>\nWrite the structure of 4-chloropentan-2-one. [1]\nAnswer:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971521_de4d1c3c66_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set II Q8\" width=\"215\" height=\"91\" \/><\/p>\n<p>Question 9.<br \/>\nHow will you convert the following?<br \/>\n(i) Propan-2-ol to propanone.<br \/>\n(ii) Phenol to 2,4,6 \u2013 tribromophenol?<br \/>\nAnswer:<br \/>\n(i) Propan-2-ol to propanone:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971556_e11b79a99f_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set II Q9\" width=\"385\" height=\"288\" \/><\/p>\n<p>Question 11.<br \/>\nWhat is the difference between oil\/water (O\/W) type and water\/oil (W\/O) type emulsions? Give an example of each type. [2]\nAnswer:<br \/>\nEmulsion of oil-in-water has oil as dispersed phase and water as the dispersion medium. For example, Milk etc.<br \/>\nEmulsion of water-in-oil has water as dispersed phase and oil as the dispersion medium. For example, Cod liver oil etc.<\/p>\n<p>Question 17.<br \/>\n(a) Which of the following ores can be concentrated by froth floatation method and why?<br \/>\nFe<sub>2<\/sub>O<sub>3<\/sub>, ZnS, Al<sub>2<\/sub>O<sub>3<\/sub><br \/>\n(b) What is the role of silica in the metallurgy of Copper? [2]\nAnswer:<br \/>\n(a) Only sulphide ores are concentrated by this process because pine oil selectively wets the sulphide ore and hence bring it to the froth.<br \/>\n(b) Silica is added in the reverberatory furnace during the extraction of copper to remove iron oxide present in the ore. Iron oxide reacts with the silica and is removed as a slag of iron silicate.<br \/>\nFeO + SiO<sub>2<\/sub> \u2192 FeSiO<sub>3<\/sub> (Slag)<\/p>\n<p>Question 18.<br \/>\n(a) Why does p-dichlorobenzene have a higher m.p. than its o- and m- isomers? [2]\n(b) Why is (-) \u2013 Butan-2-ol optically inactive?<br \/>\nAnswer:<br \/>\n(a) p-dichlorobenzene has a higher melting point than ortho and meta isomer. This is because the para isomer is having a symmetrical structure and therefore, its packing is more efficient as compared to the ortho and meta isomer, therefore, it shows a higher melting point.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574121102_37e64136dc_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set II Q18\" width=\"402\" height=\"187\" \/><br \/>\n(b) The (\u00b1) \u2013 Butan-2-ol is optically inactive because it is a racemic mixture and exists in two enantiomeric forms which are non- superimposable mirror images of each other. Both the isomers are present in equal amounts therefore, it does not rotate the plane of polarized light and is optically inactive.<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574121127_ffd0052317_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set II Q18.1\" width=\"419\" height=\"176\" \/><\/p>\n<p>Question 23.<br \/>\nWrite the names and structures of the monomers of the following polymers: [3]\n(i) Polystyrene<br \/>\n(ii) Dacron<br \/>\n(iii) Teflon<br \/>\nAnswer:<br \/>\nPolymers with their monomers and their structures:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574121177_443be082a2_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set II Q23\" width=\"408\" height=\"338\" \/><\/p>\n<p>Question 27.<br \/>\nWrite the types of isomerism exhibited by the following complexes: [3]\n(i) [CO(NH<sub>3<\/sub>)<sub>5<\/sub>Cl]SO<sub>4<\/sub><br \/>\n(ii) [Co(en)<sub>3<\/sub>]<sup>3+<\/sup><br \/>\n(iii) [CO(NH<sub>3<\/sub>)<sub>6<\/sub>] [Cr(CN)<sub>6<\/sub>]\nAnswer:<br \/>\n(i) Ionisation isomerism<br \/>\n(ii) Optical isomerism<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971661_15a8b17369_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set II Q27\" width=\"382\" height=\"206\" \/><br \/>\n(iii) Coordination isomerism<\/p>\n<h3><span class=\"ez-toc-section\" id=\"CBSE_Previous_Year_Question_Papers_Class_12_Chemistry_2013_Delhi_Set_III\"><\/span>CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set III<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Note: Except for the following questions, all the remaining questions have been asked in previous sets.<\/p>\n<p>Question 1.<br \/>\nWhat type of substances would make better Permanent Magnets, Ferromagnetic or Ferrimagnetic? [1]\n<p>Question 3.<br \/>\nWhat is the composition of \u2018Copper matte\u2019? [1]\nAnswer:<br \/>\nComposition of \u2018Copper matte\u2019 is Cu<sub>2<\/sub>S and FeS.<\/p>\n<p>Question 5.<br \/>\nWhat is a glycosidic linkage? [1]\nAnswer:<br \/>\nThe linkage between the two monosaccharide units through oxygen atom accompanied by the loss of a water molecule is called glycosidic linkage.<\/p>\n<p>Question 6.<br \/>\nWrite the IUPAC name of (CH<sub>3<\/sub>)<sub>2<\/sub>CH.CH(Cl)CH<sub>3<\/sub> [1]\nAnswer:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574121222_7b2206731a_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set III Q6\" width=\"230\" height=\"133\" \/><\/p>\n<p>Question 7.<br \/>\nWhich compound in the following pair undergoes faster S<sub>N<\/sub>1 reaction? [1]\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971776_823138e6cd_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set III Q7\" width=\"153\" height=\"58\" \/><br \/>\nAnswer:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573971836_a9b6164298_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set III Q7.1\" width=\"315\" height=\"137\" \/><br \/>\nThe carbocation formed when compounds I and II undergo S<sub>N<\/sub>1 reaction are shown below:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574121362_9a09e2e7e6_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set III Q7.2\" width=\"418\" height=\"98\" \/><br \/>\nAs 3\u00b0 carbocation is more stable than 2\u00b0 carbocation, hence compound I undergo faster S<sub>N<\/sub>1 reaction.<\/p>\n<p>Question 8.<br \/>\nWrite the structure of a p-Methylbenzaldehyde molecule. [1]\nAnswer:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573969041_8351368fbe_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set III Q8\" width=\"79\" height=\"149\" \/><\/p>\n<p>Question 9.<br \/>\nWhat is the difference between multi-molecular and macromolecular colloids? Give one example of each. [2]\nAnswer:<br \/>\nDifference between Multi-molecular and Macromolecular colloids:<\/p>\n<table border=\"2\">\n<tbody>\n<tr>\n<td style=\"text-align: center\" width=\"78\"><strong>Point of Difference<\/strong><\/td>\n<td style=\"text-align: center\" width=\"192\"><strong>Multi molecular Colloid<\/strong><\/td>\n<td style=\"text-align: center\" width=\"168\"><strong>Macro molecular Colloid<\/strong><\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center\" width=\"78\">Definition<\/td>\n<td width=\"192\">When a large number of atoms or small molecules (having diameters of less than 1 nm) of a substance combine together in a dispersion medium to form aggregates having a size in the colloidal range, the colloidal solutions thus formed are called multimolecular colloid.<\/td>\n<td width=\"168\">When substances which have very high molecular masses are dispersed in suitable dispersion medium the resulting colloidal solutions are known as macromolecular colloids.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center\" width=\"78\">Example<\/td>\n<td width=\"192\">Gold sol, sulphur sol.<\/td>\n<td width=\"168\">Starch, cellulose.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Question 14.<br \/>\n(a) Give an example of zone refining of metals<br \/>\n(b) What is the role of cryolite in the metallurgy of aluminium? [2]\nAnswer:<br \/>\n(a) Zone Refining of Metals: This method is used for the production of semiconductor and other metals of very high purity like germanium, silicon, boron, gallium and indium.<\/p>\n<p>(b) Role of Cryolite in Metallurgy of Aluminium: Cryolite is added to lower the melting point of mixture and to increase the conductivity of the electrolyte.<\/p>\n<p>Question 17.<br \/>\nAccount for the following: [2]\n(i) The C\u2014Cl bond length in chlorobenzene is shorter than that in CH<sub>3<\/sub>-Cl.<br \/>\n(ii) Chloroform is stored in closed dark brown bottles.<br \/>\nAnswer:<br \/>\n(i) This is due to a partial double bond character to C-Cl bond (due to resonance in C<sub>6<\/sub>H<sub>5<\/sub>Cl).<br \/>\n(ii) Chloroform in the presence of air gets oxidized to phosgene. Phosgene is carbonyl chloride and is represented as COCl<sub>2<\/sub>. To prevent the formation of phosgene, chloroform is stored in dark coloured bottles. The reaction represented as<br \/>\nCHCl<sub>3<\/sub> + \\(\\frac { 1 }{ 2 }\\) O<sub>2<\/sub> \u2192 COCl<sub>2<\/sub> + HCl<\/p>\n<p>Question 18.<br \/>\nHow will you convert: [2]\n(i) Propene to Propan-1-ol?<br \/>\n(ii) Ethanal to Propan-2-ol?<br \/>\nAnswer:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574118647_740f5d8dc7_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set III Q18\" width=\"347\" height=\"452\" \/><\/p>\n<p>Question 23.<br \/>\nGive the structures of products A, B and C in the following reactions: [3]\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48573968786_2763fded2e_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set III Q23\" width=\"363\" height=\"167\" \/><br \/>\nAnswer:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574118482_da47c78b90_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set III Q23.1\" width=\"381\" height=\"263\" \/><\/p>\n<p>Question 27.<br \/>\nWrite the names and structures of the monomers of the following polymers: [3]\n(i) Bakelite<br \/>\n(ii) Nylon-6<br \/>\n(iii) Polythene<br \/>\nAnswer:<br \/>\n<img loading=\"lazy\" src=\"https:\/\/infinitylearn.com\/surge\/wp-content\/uploads\/2021\/12\/48574118307_1560e972ee_o.png\" alt=\"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set III Q27\" width=\"258\" height=\"338\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Time allowed: 3 hours Maximum Marks: 70 CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Question [&hellip;]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_focuskw":"","_yoast_wpseo_title":"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi","_yoast_wpseo_metadesc":"CBSE Previous Year Question Papers Class 12 Chemistry 2013 Delhi Set I Question 1.How many atoms constitute one unit cell of a face-centred cubic crystal? 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