
	Trending ▼ ICSE CBSE 10th ISC CBSE 12th CTET GATE UGC NET Vestibulares ResFinder

CBSE Class 12 Board Exam 2020 : Chemistry (Series 5)

16 pages, 136 questions, 0 questions with responses, 0 total responses,

	cbse12	+Fave Message
	Profile Timeline Uploads Q & A

Home > cbse12 >

Instantly get Model Answers to questions on this ResPaper. Try now!
NEW ResPaper Exclusive!

Formatting page ...

Series : HMJ/5 OSS/1GRLH/1 SET 1 . Code No. . 56/5/1 - - Roll No. Candidates must write the Code on the title page of the answer-book. (I) - (I) 15 (II) - (II) - - NOTE Please check that this question paper contains 15 printed pages. Code number given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate. (III) Please check that this question paper contains 37 questions. (III) - 37 (IV) (IV) Please write down the Serial Number of the question in the , (V) - 15 (V) - 10.15 10.15 10.30 - - answer-book before attempting it. 15 minute time has been allotted to read this question paper. The question paper will be distributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the students will read the question paper only and will not write any answer on the answer-book during this period. ( ) CHEMISTRY (Theory) {ZYm [aV g : 3 K Q>o A{YH$V A H$ Time allowed : 3 hours .56/5/1. : 70 Maximum Marks : 70 322A 1 P.T.O. (i) - , , (ii) - 37 (iii) - - 1 20 - , 1 (iv) - - 21 27 - , 2 (v) - - 28 34 - -1 , 3 (vi) - - 35 37 - -2 , 5 (vii) , - , - - (viii) , , (ix) .56/5/1. 2 General Instructions : Read the following instructions very carefully and strictly follow them : (i) Question paper comprises four sections A, B, C and D. (ii) There are 37 questions in the questions paper. All questions are compulsory. (iii) Section A : Q. No. 1 to 20 are very short answer type questions carrying one mark each. Answer these questions in one word or one sentence. (iv) Section B : Q. No. 21 to 27 are short answer type questions carrying two marks each. (v) Section C : Q. No. 28 to 34 are long answer type-I questions carrying three marks each. (vi) Section D : Q. No. 35 to 37 are long answer type-II questions carrying five marks each. (vii) There is NO overall choice in the question paper. However, an internal choice has been provided in 2 questions of two marks, 2 questions of three marks and all the 3 questions of five marks. You have to attempt only one of the choices in such questions. (viii) However, separate instructions are given with each section and question, wherever necessary. (ix) Use of calculators and log tables is NOT permitted. .56/5/1. 3 P.T.O. : 1 5 - 1 , , , , (HX) XX', XX'3, XX'5 XX 7 1. ? 2. ? 3. (HF HI) 4. ? 5. X X ? 6 10 6. 7. 1 MnO4 Mn2+ ? 8. log [Ro] / [R] 9. 10. .56/5/1. 4 SECTION : A Read the given passage and answer the questions 1 to 5 that follow : The halogens have the smallest atomic radii in their respective periods. The atomic radius of fluorine is extremely small. All halogens exhibit 1 oxidation state. They are strong oxidising agents and have maximum negative electron gain enthalpy. Among halogens, fluorine shows anomalous behaviour in many properties. For example electro negativity and ionisation enthalpy are higher for fluorine than expected whereas bond dissociation enthalpy, m.p. and b.p. and electron gain enthalpy are quite lower than expected. Halogens react with hydrogen to give hydrogen halides (HX) and combine amongst themselves to form a number of compounds of the type XX , XX 3, XX 5 and XX 7 called inter-halogens. 1. Why halogens have maximum negative electron gain enthalpy ? 2. Why fluorine shows anomalous behaviour as compared to other halogens ? 3. Arrange the hydrogen halides (HF to HI) in the decreasing order of their reducing character. 4. Why fluorine is a stronger oxidizing agent than chlorine ? 5. What are the sizes of X and X in the interhalogen compounds ? Question 6 to 10 are one word answers. 6. Name the cell used in hearing aids and watches. 7. How much charge in terms of Faraday is required to reduce one mol of MnO4 to Mn2+ ? 8. Write the slope value obtained in the plot of log [Ro] / [R] Vs. time for a first order reaction. 9. Name the sweetening agent used in the cooking of sweets for a diabetic patient. 10. Name the polymer which is used for making electrical switches and combs. .56/5/1. 5 P.T.O. . 11 15 11. (a) (c) 12. H2 CO (b) (d) CO2 N2 NaOH (a) (b) (c) (d) 13. CH3CONH2 NaOH Br2 (a) CH3CH2NH2 (b) CH3CH2Br (c) CH3NH2 (d) CH3COONa 14. [Ni(CO)4] Ni (a) 0 (b) (c) 3 (d) 15. (a) (c) (b) (d) 2 4 16 20 (A) (A) (R) (R), (A) (B) (A) (R) (R), (A) (C) (A) , (R) (D) (A) , (R) 16. (A) : (R) : 17. (A) : (R) : C-O-C - 18. (A) : (R) : , .56/5/1. 6 Questions 11 to 15 are multiple choice questions. 11. In the Mond s process the gas used for the refining of a metal is (a) H2 (b) CO2 (c) CO (d) N2 12. The conversion of an alkyl halide into an alcohol by aqueous NaOH is classified as (a) a dehydrohalogenation reaction (b) a substitution reaction (c) an addition reaction (d) a dehydration reaction 13. CH3CONH2 on reaction with NaOH and Br2 in alcoholic medium gives (a) CH3CH2NH2 (b) CH3CH2Br (c) CH3NH2 (d) CH3COONa 14. The oxidation state of Ni in [Ni(CO)4] is (a) 0 (b) 2 (c) 3 (d) 4 15. Amino acids are (a) acidic (c) amphoteric (b) (d) basic neutral Questions 16 to 20. (A) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A). (B) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A). (C) Assertion (A) is correct, but Reason (R) is wrong statement. (D) Assertion (A) is wrong, but Reason (R) is correct statement. 16. Assertion (A) : Conductivity of an electrolyte increases with decrease in concentration. Reason (R) : Number of ions per unit volume decreases on dilution. 17. Assertion (A) : The C-O-C bond angle in ethers is slightly less than tetrahedral angle. Reason (R) : Due to the repulsive interaction between the two alkyl groups in ethers. 18. Assertion (A) : Low spin tetrahedral complexes are rarely observed. Reason (R) : Crystal field splitting energy is less than pairing energy for tetrahedral complexes. .56/5/1. 7 P.T.O. 19. (A) : (R) : 20. (A) : (R) : C H C C 20 1 = 20 21. ? 2 22. (a) NaCN (b) CO 1+1=2 ? 2 23. ? ? ? [Fe(CN)6]3 ( : Fe = 26) (b) ? 2 2 24. (a) 25. 26. 1+1=2 , ? 2 (i) (ii) .56/5/1. 1+1=2 8 19. Assertion (A) : Elevation in boiling point is a colligative property. Reason (R) : Elevation in boiling point is directly proportional to molarity. 20. Assertion (A) : Oxidation of ketones is easier than aldehydes. Reason (R) : C-C bond of ketones is stronger than C-H bond of aldehydes. 20 1 = 20 SECTION B 21. State Raoult s law for a solution containing volatile components. What is the similarity between Raoult s law and Henry s law ? 2 22. Write the role of (a) Dilute NaCN in the extraction of Gold. (b) CO in the extraction of Iron. 1+1=2 OR How is leaching carried out in the case of low grade copper ores ? Name the method used for refining of copper metal. 2 23. Define adsorption with an example. What is the role of adsorption in heterogeneous catalysis ? OR Define Brownian movement. What is the cause of Brownian movement in colloidal particles ? How is it responsible for the stability of Colloidal Sol ? 24. (a) (b) 2 2 Write the IUPAC name and hybridisation of the complex [Fe(CN) 6]3 . (Given : Atomic number of Fe = 26) What is the difference between an ambidentate ligand and a chelating ligand ? 1+1=2 25. How do antiseptics differ from disinfectants ? Name a substance which can be used as a disinfectant as well as an antiseptic. 2 26. Identify the monomers in the following polymers : (i) (ii) .56/5/1. 1+1=2 9 P.T.O. 27. (i) H2S2O8 (ii) XeF6 1+1=2 : 0.01 m 0.068 C [ Kf = 1.86 K kg mol 1] 3 A B ZnSO4 CuSO4 , 2A B 2g Cu ? A Zn ? [ Cu = 63.5 g mol 1, Zn = 65 g mol 1; 1F = 96500 C mol 1] 3 28. AlCl3 29. 30. 31. (i) (ii) (iii) 1+1+1=3 A, B, C, D, E F 6 =3 32. (i) H2O2 (ii) 358 K 20% H3PO4 (CH3)3C OH (iii) HI ? (i) o- (ii) (iii) .56/5/1. 3 1=3 1+1+1=3 10 27. Draw the structures of the following : (i) H2S2O8 (ii) XeF6 1+1=2 SECTION : C 28. A 0.01 m aqueous solution of AlCl3 freezes at 0.068 C. Calculate the 29. percentage of dissociation. [Given : Kf for Water = 1.86 K kg mol 1] 3 When a steady current of 2A was passed through two electrolytic cells A and B containing electrolytes ZnSO4 and CuSO4 connected in series, 2 g of Cu were deposited at the cathode of cell B. How long did the current flow ? What mass of Zn was deposited at cathode of cell A ? [Atomic mass : Cu = 63.5 g mol 1, Zn = 65 g mol 1; 1F = 96500 C mol 1] 3 30. Differentiate between following : (i) Amylose and Amylopectin (ii) Globular protein and Fibrous protein (iii) Nucleotide and Nucleoside 1+1+1=3 31. Identify A, B, C, D, E and F in the following : 6 =3 32. Give the structures of final products expected from the following reactions : (i) Hydroboration of propene followed by oxidation with H2O2 in alkaline medium. (ii) Dehydration of (CH3)3C OH by heating it with 20% H3PO4 at 358 K. (iii) Heating of with HI. OR How can you convert the following ? (i) Phenol to o-hydroxybenzaldehyde. (ii) Methanal to ethanol (iii) Phenol to phenyl ethanoate. .56/5/1. 11 3 1=3 1+1+1=3 P.T.O. 33. (i) - (ii) (iii) 3 1=3 34. (i) (ii) 3 (iii) 1 + 1 + 1 = 3 : 35. (a) (b) (a) (b) (c) (i) (ii) (iii) Zn, Cd Hg (i) Na2CrO4 Na2Cr2O7 (ii) MnO2 K2MnO4 (i) Ti3+ Sc3+ (ii) Cr2+ 2 3 MnO4 + 4H+ 36. (a) 3+2=5 2+2+1=5 (i) NaOH CH3CHO (ii) H2N NH NaOH (b) (iii) .56/5/1. (i) CH3 CH = CH CO CH3 CH3 CH2 CO CH = CH2 (ii) 12 3 + (1 + 1) = 5 33. Give reasons : (i) Aniline does not undergo Friedal-Crafts reaction. (ii) Aromatic primary amines cannot be prepared phthalimide synthesis. (iii) Aliphatic amines are stronger bases than ammonia. by 34. Write three differences between lyophobic sol and lyophilic sol. OR Define the following terms : (i) Protective colloid (ii) Zeta potential (iii) Emulsifying agent 35. (a) (b) (b) (c) K2MnO4 from MnO2 2+2+1=5 Write the products formed when benzaldehyde reacts with the following reagents : (i) CH3CHO in presence of dilute NaOH (ii) H2N NH (iii) Conc. NaOH Distinguish between following : (i) CH3 CH = CH CO CH3 and CH3 CH2 CO CH = CH2 (ii) .56/5/1. 1+1+1=3 OR Account for the following : (i) Ti3+ is coloured whereas Sc3+ is colourless in aqueous solution. (ii) Cr2+ is a strong reducing agent. Write two similarities between chemistry of lanthanoids and actinoids. Complete the following ionic equation : 2 (b) 3 3+2=5 3 MnO4 + 4H+ 36. (a) 3 1=3 SECTION : D Give reasons : (i) Transition metals and their compounds show catalytic activities. (ii) Separation of a mixture of Lanthanoid elements is difficult. (iii) Zn, Cd and Hg are soft and have low melting point. Write the preparation of the following : (i) Na2Cr2O7 from Na2CrO4 (ii) (a) Gabriel s Benzaldehyde and Benzoic acid. OR 13 3 + (1 + 1) = 5 P.T.O. (a) (i) CH3 CH3 (ii) Zn/Hg C = O HCl NaOH/CaO (a) DIBAL-H (iii) CH2 = CH CH2 CN (b) H3O+ (b) CH3COCH3, HCHO, CH3CHO, (c) 2, 4 . . . 3+1+1=5 25% 40 80% ? (b) 3+2=5 (a) 50% 300 K 30 320 K 10 (Ea) 37. (a) (R = 8.314 J K 1 mol 1) (b) (c) ? [ log 2 = 0.3010, log 3 = 0.4771, log 4 = 0.6021, log 5 = 0.6991] 3+1+1=5 ___________ .56/5/1. 14 (a) Write the final products in the following : (i) CH3 CH3 (ii) Zn/Hg C = O Conc HCl NaOH/CaO (a) DIBAL-H (iii) CH2 = CH CH2 CN (b) H3O+ (b) Arrange the following in the increasing order of their reactivity towards nucleophilic addition reaction : CH3COCH3, HCHO, CH3CHO, (c) 37. (a) (b) Draw the structure of 2, 4 DNP derivative of acetaldehyde. 3+1+1=5 A first order reaction is 25% complete in 40 minutes. Calculate the value of rate constant. In what time will the reaction be 80% completed ? Define order of reaction. Write the condition under which a bimolecular reaction follows first order kinetics. 3+2=5 OR (a) A first order reaction is 50% complete in 30 minutes at 300 K and in 10 minutes at 320 K. Calculate activation energy (Ea) for the reaction. (R = 8.314 J K 1 mol 1) (b) Write the two conditions for collisions to be effective collisions. (c) How order of reaction and molecularity differ towards a complex reaction ? [Given : log 2 = 0.3010, log 3 = 0.4771, log 4 = 0.6021, log 5 = 0.6991] 3+1+1=5 ___________ .56/5/1. 15 P.T.O. .56/5/1. 16

Formatting page ...

Tags : cbse, cbse papers, cbse sample papers, cbse books, portal for cbse india, cbse question bank, central board of secondary education, cbse question papers with answers, prelims preliminary exams, pre board exam papers, cbse model test papers, solved board question papers of cbse last year, previous years solved question papers, free online cbse solved question paper, cbse syllabus, india cbse board sample questions papers, last 10 years cbse papers, cbse question papers 2017, cbse guess sample questions papers, cbse important questions, specimen / mock papers 2018.

cbse12 chat

Horizontal lines at:
Guest Horizontal lines at:
AutoRM Data:
Box geometries: