CBSE Class XII Model Paper of Chemistry (Model Papers) 2012

Advertisements

 

1. Point defect Decreases the density of a crystal? (1)

2. What is the primary structural feature necessary for a molecule to make it useful in a condeusation pdymesisation reaction? (1)

3. What is the number of atoms in a unit cell of FCC crystal? (1)

4. Arrange the following compaunds in an increasing order of basic strength in their aqueaus solutions (1)
NH3 , CH3NH2 , (CH3)2 NH , (CH3)3 N

5. Write the IUPAC name of (CH3)2 CH-CH2,-C-CH(CH3)2 (1)

6. Why is electrolytic reduction preferred over chemical reduction for the isolation of certain metals? (1)

7. What is the role of depressant in froth floatation process? (1)

8. What is the percentage efficiency of packing in case of a metal crystal for body centred cubic structure? (1)

9. A copper-silver cell is set up. The copper ion concentration in it is 0.10 M the silverion canc. is not known. the cell potential mearured 0.422 V. Determine the conc. of silver ion in the cell, Given E0Ag+=0.80v, E0cu2+/cu=+0.34v (2)

10. Describe the role of the following :- (2)

(i.) NaCN in the extraction of silver from a silver ore
(ii.) Cryolite in the extraction of aluninium from pure alumina

11. Differentiate between condensation and addition polymerisation. Give one example each of the resulting polymers. (2)

12. Explain the mechanism of aid dehyhration of ethanol to yield ethene. (2)

13. Draw the structures of (i) Xef2 (ii)H3Po4 (2)

(i) Rusting of iron in saline water

(ii) Iron does not rust even if zinc coating is broken

14. Describe the following with on example of each. (2)

(i) Reimer-Themann Reaction

(ii) Sandmeyer Reaction

OR

Describe the follwing reactions with one example of each

(i) Friedal- Craft reaction

(ii) Cannizzaro Reaction

15. Complete the following chemical reaction equations (2)

(i) Xef2+H2O

(ii) PCl5+H2O

16. Complete the following chemical reaction equation:- (2)

(i) MNO4+ C2O42-+ H+

(ii) Cr2O72-+ Fe2++ H+

17. Enumerate the reactions and facts of D-glucose which cannot be explained by its open chain structure. (2)

18. A first order reaction has a rate constant of 0.0051 min-1 If we begin with O.10M Canc. of reactant, What conc. of the reactant will be left after 3 hours. (2)

19. Calculate the cell emf and Drgo for the following at 25oc Zn(s)/Zn2+(0.1M) 11 Cd2+ (0.01M)/ Cd(s) Given EoZn2+/Cd=-0.763 Volt, 1F=96500 C mol-1, R=8.314 JK-1 Mol-1

OR

Calculate the standard electrode potential of Ni2+/Ni electrode if emf of the cell Ni(s)/Ni2+/Ni2+(0.01 m)II Cu2+ (0.1M)I Cu(s) is 0.59volt Given Eo Cu2+/Cu = +0.34 Volt

20. Explain the following

(i) Electrophoresis (ii) Dialysis (iii) Tyndall effect

21. (i) What is spectro chemical series 1×3=3

(ii) Show the splitting of degenerate d-crbitals occarding to crystal field theory.

(iii) How the configuration of d-orbitals is decided on the basis of pairing energy?

22. Explain the following observations :-

(i) These are two -NH2 groups in semi carbazide but only one is involved in the formation of semicarbazone

(ii) Phenols are more acidic than alcohols

(iii) Alkyl halider when react with alcohlic KOH, forms alkenes.

23. Give reason for the following observation :-

(i) Of the d4 species, Cr2+ is strongly reducing where as Mn (III) is strongly oxidising.

(ii) The enthalpies of atomization of the transition metals are quite high.

(iii) Interstitial compounds are well known for transition metals.

24. Compound a C6H12O2 on reduction with liA2H4 yields two compounds B and C. The compound B On oxidation gave D which on treatment with aqueous alkali and subsequent heating furnished E. The latter on catalytic hydrogenation gave C. The compound D on further oxidation gave CH3COOH Deduce the structure of A,B,C,D and E.

25. Define the following and give one example of each

(i) Antihistamine (ii) Antacids (iii) Antibiotics

26. Calculate the freezing point of a solution containing 18 g glucose C6H12O6 and 68.4 g sucrose C12H22011 in 200g of water the freezing point of pure water is 273 K and Kf for water is 1.86 K Kg mol-1

OR

What conc of nitrogen should be present in a glass of water at room temperature? Assume a temperature of 25oC, a total pressuse of 1 atm and mole fraction of nitrogen in air of 0.78 (KH for nitrogen=8.42X10-7M/mm Hg)

27. The half life for a first order reaction is 5 x 104s. What percentage of the initial reactant will react in 2 hours. (3)

28. (a) Draw the structure of (i) H2S2O8 (ii) HCLO4 (2+3)

(b) How would you account for the following :

(i) NH3 is a stronger base than PH3

(ii) Sulphur has a greater tendency for catenation than oxygen.

(iii) F2 is a stronger oxidising agent than Cl2

OR

(b) Arrange the following in the increasing order of property indicated.

(i) H-F H-Cl H-Br H-I acidic nature.

(ii) NH3< /sub> PH3 AsH3 SbH3 B1H5 Basic nature.

(iii) H2O H2S H2Se H2Te H2Po Boiling point.

29. (a) Write the chemical reaction to illustrate the following : (2+3)

(i) Rosenmund reduction (ii) Aldol condensation.

(b) Distinguish between the following pairs :

(i) Propanal and propanone

(ii) Acetophenone and Benzophenone

(iii) Phenol and Benzoic acid.

OR

(a) Convert the following

(i) Ethanol to 3-hydroxybutanal

(ii) Benzaldehyde to Benzophenone

(b) An Organic compound A has the molecular formula C8H16O2 It gets hydrolysed with dil sulphuric acid and gives a carboxylic acid B and on alcohol C. C,on oxidation with chromic acid also produced B C on dehydration given but-1end write equation for the reactions involved.

30. (i) Write the preporation of potassium permanganate crystals from its ore. How KMnO4 act as an oxidising agent in acidic medium

(ii) What happens when acidic KMNO+ reacts with a (a)HI (b) FeSo4 (c) C2H2O4

OR

(i) Write the preparation of potassium dichromate is crystals for its are.

(ii) What happens when potassium dichromate is treated with acid and with base.

(iii) Draw the structure of chromate and dichromate ion.

(iv) Write the ionic equation when potassium dichromate reacts with SnCl2 and with FeCl2 in acidic medium.

(a.) What are transition elements? What is the difference between the electronic configurations of transition and inner transition elements?

By:- Amar Ujala

Also see:

For further information regarding CBSE Class XII Model Paper of Chemistry (Model Papers), connect with us on facebook, google+ and twitter.


Tags: chemistry sample papers for class 12 with answers, cbse solved sample papers 2013 for class 12 chemistry, chemistry sample papers for class 12 cbse 2013, cbse class 12 chemistry sample paper 2013 with solutions, cbse class 12 chemistry sample paper 2013, chemistry sample paper class 12 with solution, cbse sample papers for class 12 2013 chemistry, Chemistry Model paper 2013, sahodaya model question papers class 12 2014, what is crystal answer - cbse 12


Ask a Question:

  • please send me the solutions of these questions..then i can understand very well…..

    tanvi jain on 07 Mar 2013
  • nice questions…..but how to download them???
    it will help me a lot in exams…thank you

    sanya on 27 Feb 2013
  • Can you send the solutions of this question paper?it will be very much helpful to me

    rainy ali on 20 Feb 2013
  • Can you send the solutions of this question paper?it will be very much helpful to me.

    sneha on 01 Feb 2013
  • what is friedal craft, cannizzaro, reimer-themann, sandmeyer reaction reaction.

    SHUBHAM RAO on 27 Dec 2012
  • Please send me the solution of all question of this sample paper then i can understand it well

    Ankita sandhu on 25 Dec 2012
  • i request you to sent me the answers so i can use this information usefully

    jumail ahmed on 21 Dec 2012
  • please send me the solution of every question of this sample paper then i can understand very well

    Radhika Gairola on 08 Sep 2012
  • I want all answers of this sample paper so that i can solve all the questns pls send me the solutions

    Priyanka on 22 Jul 2012
  • caluclate freezing point of solution containing 18g of glucose and 68.4g of sucrose in 200g of water freezing point of pure water is 273k and kf of water is 1.86k kg/mol

    meenakshi on 25 Jun 2012
  • please send me the solution for this model paper. i want every question to be answered

    anjana on 17 Jan 2012
  • I WANT SOLVED LAST 10 YEARS BOARD EXAM PAPERS OF CLASS12 OF physics chemistry maths computer science and english

    SANDY on 24 Dec 2011
  • Plz send me solved paper of this paper.Every answer of this i want solved.

    Tawqeed Khan on 28 May 2011
  • i want solved papers of this model paper.every answers of this ans i want solved

    nadia on 30 Apr 2011
  • i want some sample papers for 12th class with biology
    i want some tips to get a higher percentage

    prasant sahu on 23 Apr 2011
  • i want a solved sample paper of this model paper. every answers of this i want solved

    vijay on 15 Mar 2011
  • i need solution of this model paper…………………..plzzzzzzzzzzz send it as fast as possible……….

    divya sree on 04 Mar 2011
  • PLEASE SEND ME THE ANSWERS OF ALL THESE QUESTIONS.PLEASE ANSWER ALL THE ABOVE QUESTIONS

    ANNA R. THOMAS on 03 Mar 2011
  • I WANT SOLVED PAPERS OF THIS MODEL PAPER. answers to all of these questions in the model question paper

    manish on 02 Mar 2011
  • sir, i want to know the difference b/w molar mass and atomic mass.and pure vapour pressure and vapour pressure of sol.

    dalchand on 02 Mar 2011
  • which selected chapters of PCM should i prepare to score MARKS above THAN 80%……………PLZ REPLY ITS VERY IMPORTANT

    NITYA NAND on 13 Feb 2011
  • What are the transition elements?what are the difference between the electronic configuration of transition and inner transition elements?

    Davie on 18 Jan 2011
  • can i hav all the name reaction in the whole organic chemistry with explaination……………

    vishu on 14 Jan 2011
  • where can I find answers to all of these questions in the model question paper

    atul on 11 Jan 2011
  • i want the solutions of this model test paper……..i wnant the solution of every question…..

    aditya on 29 Dec 2010
  • I WANT SOLVED PAPERS OF THIS MODEL PAPER.EVERY ANSWERS OF THIS QUESTION I WANT SOLVED

    SUBIR BHAUMIK on 23 Dec 2010
  • I WANT SOLVED PAPERS OF THIS MODEL PAPER.EVERY ANSWERS OF THIS ANSWERS I WANT SOLVED

    SUBIR BHAUMIK on 23 Dec 2010