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

CBSE Class 12 Pre Board 2020 : Chemistry (Kendriya Vidyalaya (KV) Agra)

8 pages, 81 questions, 0 questions with responses, 0 total responses,

	CBSE 12 Pre Boards	+Fave Message
	Profile Timeline Uploads

Home > cbse12_pre_boards > F Also featured on: School Page cbse12

Formatting page ...

KENDRIYA VIDYALAYA SANGATHAN,AGRA REGION (SET-H) PRE BOARD EXAMINATION 2019-20 CHEMISTRY (Theory) Class: XII Time: 3 Hrs. Max. Marks: 70 GENERAL INSTRUCTIONS:(a) All questions are compulsory. (b) Section A: Q.Nos. 1 to 20 are very short answer questions (objective type) and carry 1 mark each. (c) Section B: Q.Nos. 21 to 27 are short answer questions and carry 2 marks each. (d) Section C: Q.Nos.28 to 34 are long answer questions and carry 3 marks each. (e) Section D: Q.Nos. 35 to 37 are also long answer questions and carry 5 marks each. (f) There is no overall choice, However an internal choice has been provided in two questions of two marks, two questions of three marks and all the three questions of five marks weightage . You have to attempt only one of the choices in such questions. (g) Use log tables if necessary, use of calculators is not allowed. SECTION A Passage Based Questions ( Q.Nos 1 to 5) Read the given passage and answer the questions 1 to 5 that follow: The equations derived for colligative properties are based on the assumption that solutions are dilute and solute molecules do not dissociate or associate in solution. Discrepancies in determination of molar masses or measuring colligative properties arise when the solute dissociates or associates on dissolving in the solution, the number of molecules undergo a change. Van t Hoff introduced a factor called Van t Hoff factor ( i) to express the extent of association or dissociation of solute. 1. Electrolyte A gives 4 ions and B is a non-electrolyte, if 0.1 molar solution of solute B produces an osmotic pressure p then what will be osmotic pressure produced by 0.02 molar solution of A? 1 2. 0.2 m aqueous solution of a weak acid (HX) is 20% dissociated. Find the boiling point of this solution (Kb for water =0.052 Km-1) 1 Page 1 of 8 1 3. Which of following equimolar solution is expected to have lowest freezing point? 0.5 M H3PO3 , 0.5M Na3PO3, 0.5M NaCl, 1 0.5 M Aniline 4.The ratio of elevation in boiling point for 1M Urea , 1M Glucose, 1M NaCl and 1M K2SO4 in one of the following is .. (a)1:1:2:3 1 (b) 3:2:1:1 (c) 1:2:3:4 (d) 2:2:3:4 5. What will be effect on the colligative property of a molecule due to its association? 1 One Word Answer Type Questions (QNos 6 to 10) 6. Out of C and CO which is a better reducing agent for FeO at reduction zone? 1 7. Which is thermally more stable ClF or ICl? Give reason. 1 8. Write a chemical equation when PtF6 and Xenon are mixed together. 1 9. FeSO4 solution mixed with ( NH4)2SO4 solution in 1:1 molar ratio gives the test of Fe2+ ion but CuSO4 solution mixed with aqueous ammonia in 1:4 ratio does not give the test of Cu2+ ion. Why? 1 10. Using IUPAC norms, write the formula of tetrahydroxozincate(II) 1 Multiple Choice Questions ( QNos 11 to 15 ) 11. Which is correct formula of Freon-12? (a) CCl2F2 (b) CF3Cl 1 (c) CHCl2F (d) CCl3F 12. Which of the following is not chiral? 1 (a) 3-Bromopentane (b) 2, 3-dibromopentane (c) 2-Hydroxypropanoic acid (d) Butan-2-ol. 13. Mono chlorination of Toluene in sunlight followed by hydrolysis with aqueous NaOH Yields: (a) o-cresol 1 (b) m- cresol (c) 2,4-dihydroxy toluene (d) benzyl alcohol 14. The reagent that does not react with both, Acetone and Benzaldehyde : 1 (a) Sodium hydrogen sulphite(b)Phenyl hydrazine (c)Fehling s solution (d)Grignard reagent 15. Which one of the following is stored in the liver of animals? (a) Amylose (b) Cellulose (c)Amylopectin Page 2 of 8 2 1 (d) Glycoge Questions 16 to 20: The question given below consist of an Assertion and Reason .Use the following key to choose the appropriate answer: (A)If both assertion and reason are correct and reason is correct explanation of the assertion. (B) If both assertion and reason are correct but reason is not the correct explanation of the assertion. (C)If Assertion is correct but reason is wrong statement. (D) If assertion is wrong, but reason is correct statement. 16. Assertion: D (+)-Glucose is dextrorotatory in nature. 1 Reason: D represents its dextrorotatory in nature 17. Assertion Vitamin D can be stored in our body. 1 Reason Vitamin D is fat soluble vitamin. 18. Assertion Most of the synthetic polymers are not biodegradable. 1 Reason Polymerisation process induces toxic character in organic molecules. 19. Assertion For making rubber synthetically, isoprene molecules are polymerized. 1 Reason Neoprene is a synthetic rubber. 20. Assertion Dacron is a copolymer. 1 Reason Dacron is prepared by addition polymerization of ethylene glycol and terephthallic acid. SECTION B 21. Describe the method involved for concentration of Bauxite Ore. 2 22. 2.5 g Ethanoic acid (CH3COOH) is dissolved in 75 g of Benzene. Calculate the molality of the solution. 2 OR What is the mole fraction of the solute in 2.5 m aqueous solution? Page 3 of 8 3 23. How will rate of a reaction change when [A]0 is doubled and tripled for : 2 (i) zero order reaction. (ii) Second order reaction. OR Derive an expression to determine half life period of zero order reaction. 24. Complete the following reactions in balanced equation: (a) Cr2O72-(aq) (b) MnO-4 (aq) + Cl- (aq) 2- + H+(aq) 2 + + C2O4 (aq) + H (aq) 25. With the help of Crystal field theory , predict the number of unpaired electrons in.. 2 [Fe(CN)6]4- and [ Fe(H2O)6]2+ complexes. 26. What happens when? 2 (a) 2- Butyl chloride is treated with alcoholic KOH. (b) Chlorobenzene is subjected to hydrolysis. 27. Though NH2 group is o- and p- directing , a significant amount of m- derivative is also Formed during nitration of aniline Then how can you prepare p-nitro aniline from aniline? 2 28.Note: Only for visually impaired students. Explain the variation of conductivity and molar conductivity with dilution of solution. Page 4 of 8 4 3 28. The Following Curve is obtained when molar conductivity ^m is plotted against square root of concentration c1/2 along y and x axis respectively for the two electrolytes x and y 3 600^ m (Scm2 mol-1) 400200x Y 0.2 0.4 0.6 1/2 -1 1/2 C (mol L ) View the diagram and answer the following. (i) How can you determine ^ m for these electrolytes? (ii) How do you account the increase in ^m for the electrolytes x and y with dilution. OR Explain 29. 3 (i) Kohlrausch low (ii) Molar conductivity (iii) Nickel cadmium storage cell The Following data were obtained during the first order thermal decomposition of N2O5 (g) at constant volume, 2 N2O5 (g) 2N2O4(g) 2 N2O5 (g) + O2 (g) S.No. Time (s) Total Pressure (atm) 1. 2. 0 100 0.5 0.512 Calculate the rate constant Page 5 of 8 5 3 30. (i) Why are lyophilic colloidal sols more stable than lyophobic colloidal sols? 3 (ii) What is observed when sodium chloride is added to a colloidal solution of ferric hydroxide? OR Explain 31. 3 (iv) Peptization (v) Electrophoresis (vi) Hardy Schulze rule (i) Why the melting and boiling points of Zn, Cd, and Hg are low while V, Cr and Mn are high? 3 (ii) Write changes with K2Cr2O7 on its action with alkalies . (iii) There is greater range of oxidation states among the actinoids as compared to lanthanoids. Explain. 32. 33. (a) Give the reaction mechanism of acid catalysed addition of water to propene. (b) Write the preparation of picric acid. (c) Williamson s synthesis. (Write short notes) (a) Distinguish between 3 3 CH3CH2NH2 and CH3-NH-C2H5 (b) Write UPAC name of CH3-CH2-CH CH2-CH3 NH-CH3 34. (c) Convert Aniline into benzene. (a) Give one example of each (i) Antimicrobials (ii) Antifertility drugs 3 (c) What kind of medicine Equanil is ? Page 6 of 8 6 Section D 35. (a) Calculate the Standard electrode potential of Ni2+/Ni electrode if the cell 3+2 Potential of the cell: Ni/Ni2+(0.01M) II Cu2+ (0.1M)/Cu is 0.59 V given E0Cu2+/cu=0.34 V (b) State Faraday s first law of electrolysis and define electrochemical equivalent. OR (a) A solution of CuSO4 is electrolysed for 10 minutes with a current of 1.5 amperes, what is the mass of copper deposited at cathode? (Atomic mass of Cu=63) (b) Which type of cell is used in transistors? Write the reactions taking place at anode and cathode in this cell. 36. (a) Give Reasons: 3+2 (i) SF6 is not easily hydrolysed. (ii) Noble gases have very low boiling points. (iii) Boiling points of inter halogens are little higher as compared to reactions to pure Halogens. (b) Complete the reactions. (i) XeF2 +H2O (ii) Fe3++SO2+ H2O OR (a) Arrange the following in order of property indicated for each set. (i) F2,Cl2, Br2, I2, - increasing bond dissociation enthalpy. (ii) H2O, H2S, H2Se, H2Te increasing order of bond angle. (iii)HF, HCl, HBr, HI - increasing order of acid strength. (b) Draw the structure of (i) XeOF4 (ii) ClF3 Page 7 of 8 7 37. (a) Complete the following reactions. 3+2 (i) CH3CHO+ C2H50H (ii) C6H5 CHO + H2NCONHNH2 CH3 (iii) (b) Give one example in each (complete equations) for the following. (i) Aldol condensation (ii) Cannizzaro reaction. OR (a) (i) Write IUPAC name of HOOC-CH2-CH CH2-COOH COOH (ii) Distinguish between CH3 CHO and CH3 CH2 CHO (iii) What is Schiff s base? (b) Convert the following. (i) Methanal into Ethanal (ii) Ethanoic acid into chloroethanoic acid END OF THE PAPER Page 8 of 8 8

Formatting page ...

Tags : cbse pre boards, prelims 2015 - 2016, preliminary examinations, central board of secondary education, india schools, free question paper with answers, twelfth standard, xiith std, board exams, mock, model, sample, specimen, past, free guess papers.india, delhi, outside delhi, foreign, cbse class xii, cbse 12, 12th standard, cbse papers, cbse sample papers, cbse books, portal for cbse india, cbse question bank, cbse question papers with answers, 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 questions papers, cbse important questions, specimen / mock papers.

cbse12_pre_boards chat

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