CBSE MODEL TEST PAPER – 2010
XII – Chemistry |
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| 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
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| (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 1x3=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 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? |
