XII,CHEMISTRY (043) CBSE BOARD PAER-2018-SET-2

               

                 CLASS - XII CHEMISTRY MODEL PAPER II– (043)—2018

  Time : Three hour                                                                 Max. Marks : 70

General Instructions :-

 1. All questions are compulsory.
 2. Question No. 1-5 are very short answer questions and carry 1 mark each.
 3. Question No. 6-10 is short answer questions and carries 2 marks each.
 4. Question No. 11-22 is also short answer questions and carries 3 marks each.
 5. Question No. 23 is value added questions and carry 4 marks.
 6. Question No. 24-26 carry 5 marks
 7. Use log tables if necessary, use of calculators is not allowed.

 Q1.What do you mean by F-center.?                                                                            1

 Q2. Why sulphide ores is extracted by froath flotation process.?                                  1

Q 3. Why Zn,cd,Hg are not considered transition elements,yet they are present in d- 

         block.?                                                                                                                    1

 Q4. Write IUPAC name of the following compound                                                        1

 Q5.What do you mean by ferromagnetism.?                                                                  1

                                       K

Q6.Consider the reaction A ——— P. The change in concentration of A with time is shown in the following plot :

            (i)         Predict the order of the reaction.

            (ii)        Derive the expression for the time required for the completion of the   

                 reaction.?                                                                                                         2

Q7.   (i)What do you mean by activation Energy.?

         (ii) The rate constant of a reaction is LogK   =A.^e-28000k/T .Calculate activation energy.                                                                                                                                           2

Q8.Drow the structure of

            (i)H₂SO₅         (ii) H₃PO₄.                                                                                    2

Q9. For the cell reaction :

                        Ni (s) / Ni2– (aq) // (aq) Ag+ (aq) / Ag

            Calculate the equilibrium constant at 25 °C. ?

                        E° Ni2+/Ni = – 0.25 V and E° Ag+/Ag = 0.80 V                                2                                        

                                                                         OR

Represent the cell and calculate the EMF of the cell in which the following reactions takes place :

            Mg (s) + 2 Ag+ (0.0001 M) ——— Mg2+ (0.130 M) + 2 Ag (s)

            E°cell = 3.17 V

Q10. The vapour pressure of pure benzene at a certain temperature is 0.850 bar. A non volatile non-electrolyte solid weighing 0.5 g is added to 39 g of benzene. The vapour pressure of the solution is 0.845 bar. What is the molar mass of the solid substance.?                                                                                                                                                 2

 Q11.   Write the chemical reaction which occour when glucose react with

              (i) Hydroxyl amine.
              (ii)Red phosphorous and HI.

             (iii)Oxidised by KMnO₄ .                                                                                    3                                                                                    

Q12. Explain the following:-

            (i)What defeciency desease caused by vitamins E.Write their sources.?
            (ii)Why aspartame may be dangerous to take in hot food.?
            (iii)What are broad spectum antibiotic.?                                                                                      3

 Q13. Define the followings:-

           (i) What is calcination and roasting.?

           (ii) After heating the egg,where it water goes.?                                                     3

 Q14. (i)Define molar conductivity.How it chane with change in dilution.                         2   

           (ii)How much faraday will be required to deposit 27 gm of aluminium from aq Alcl₃              1

           

Q15. (a)Write short notes on the following name reaction :  

         

                (i) Hoffmann Reaction
              (ii)Halloform Reaction                                                                                          2

         (b)Why we use dry ether in wurtz reaction.?                                                         1         
                                                                                              

 Q16. (a)Write chemical tests to distinguish between compounds in each of the                                     following pairs:

                (i) Phenol and Benzyl alcohol
                (ii) Formaldehyde and acetaldehyde                                                                 2

           (b)Pkb of aniline is more then that of methyl amine. ?                                            1

                                     

 Q17.(a)Arrange the following compounds in

               HclO,HclO₂,HclO₃,HclO₄                                (Acidity order)                                   1

                                                           

           (b) What are dispropotanation reaction.Give an example takin phosphorous         2
             
 Q18.Explain with suitable reason

         (a)Aniline doesn’t give Friedal craft reaction.Explain.?.

        (b) Arrange the following in increasing order of basic strength :

                   C6H5NH2, C6H5N (CH3)2, (C2H5)2 NH and CH3NH2                                  3

Q19.   An organic compound contain 69.77% carbon, 11.63% hydrogen and rest oxygen.

        The molecular mass of compound is 86. It does not reduce Tollen’s reagent but form an addition compound with sodium hydrogen sulphide and give positive iodoform test. On vigorous oxidation it gives ethanoic and propanoic acid. Write the possible structure of the compound.                                                                                      3

OR

            An organic compound (A) having molecular formula C9H10O form an orange red 

           precipitate  (B) with 2, 4 — DNP reagent. Compound (A) gives a yellow precipitate  

         (C) when heated in the presence of iodine and NaOH along with a colourless 

           compound (D). (A)  does not reduceTollen’s reagent or Fehling’s solution nor does it 

          decolourise Bromine water. On drastic oxidation of (A) with chromic acid, a carboxylic

            acid (E) of molecular formula C7H6O2  is formed. Deduce the structure of organic 

             compounds A to E.      

Q20. Write names of monomer/s of the following polymers and give important uses..

 (a) Buna-N and Buna-S
            (b) Polyacrlonitrile 

(c) Melamine – formaldehyde polymers                                                               3

Q21. (a) Which isomerism can be shown by the comlex given : [Co(H₂O) (SO₄)]Cl

         (b) [Co(NH3)6]3+ is diamagnetic whereas [Co(F6)]3– is paramagnetic. Give reasons.?                                                                                                                                           3

 Q22  (a) Caesium Chloride crystallizes as a body centered cubic lattice and has a density 

                 of 4 g/cm³.Calculate the length of the edge of the unit cell of Caesium Chloride                       Crystal ? (Molar Mass of CsCl = 168.5 g/mol)

         (b) Give example which show Schottky as well as frenkel defect                              3

 Q23. Ram and shyam work in a factory. They work hard a lot. After few days Ram 

         suffering from lungs problem. He feeling problem in breathing. And shyam suffering 

           from posy jaw.

     Answer the following from the passage

          (i)when colloidal particle come in air they commonly known as-----

          (ii)What product produced by factory,which is commonly used by Humane beings.

          (iii)What are the suggestion for ram and shyam?

          (iv)What is possy jaw.?                                                                                                 (4)

 Q 24. (a)       What is the effect of pH on the K2Cr2O7 solution ?

            (b)       Transition metal exhibit higher enthalpies of atonisation, explain why ?

            (c)        Why the transition metal generally form coloured compounds ?

            (d)       Which out of the following are transition element and why ?

                        Zn, Ag, Cd, Au

          (e)Why is the separation of lanthanide elements difficult ?                                      5

OR

            (a)       Transition metal and their many compounds act as good catalyst.

       (b)       Actinoid contraction is greater from element to element than lanthanoid contraction. Why ?

          (c)        K2PtCl6 is a well known compound whereas corresponding Ni compound is not known. State a reason for it.

          (d)       A mixed oxide of Iron and Chronium FeO . Cr2O3 is fused with Na2CO3 in presence of air to form a yellow coloured compoud A. On acidification the compound (A) form an orange coloured compound (B) which is a strong oxidizing agent.

                        (a)       Identify A and B.

                      (b)       Write balanced chemical equation for each step.

 Q25. Arrange the following in the order of property indicated for each set :                                   5

            (a)       F2, Cl2, Br2, I2                                  ; Increasing Bond Energy

            (b)       HF, HCl, HBr, HI                               ; Increasing acid strength

            (c)        NH3, PH3, AsH3, BiH3                   ; Increasing base strength

            (d)       H2O,  H2S, H2Se, H2Te                 ; Increasing acid strength

            (e)       NaF, NaCl, NaBr, NaI                      ; decreasing ionic character

OR

            (a)       How are XeO3 and XeF4 prepared ? Draw their molecular shape.

            (b)       Write the formulae of the noble gas compound that is isostructural with

                        (i)IBr2–                                    (ii)BrO₃^–

                 (c) What are interhalogens,why they are more reactive then halogens.?

Q 26.     (a) Consider the adsorption isotherms given below and interpret the variation in the

                 extent of  Adsorption (x/m) when

                       (i) temperature increases at constant pressure

                       (ii) Pressure increases at constant temperature

               (b) Name the catalyst and the promoter used in Haber’s process for manufacture of  

                  Ammonia.   

             (c) What are Zeolite.?

             (d)Why heat of adsoption is more in chemiosoption then physiosorption.?    5                                                                                                                                                                                                       

                                                                        OR

             (a) What do you mean dialysis.?

             (b) What is Brownion movement.?
             (c) What happen when Fecl₃ is mied in water.?                                                           
             (d) What is lyohilic and lyophobic sol.?

             (e) What is positive adsorption.?                                                                           

*********************************************************

                                                                                    DR SUDHIR TOMAR

                                                  (M.Sc(inorganic chemistry),M.SC(physical chemistry)

                                                   M.Ed,ph.D

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