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Download CBSE Guess Paper Biotechnology Class XII (12th) 2008

Guess Paper – 2008

Class – XII

Subject – Chemistry (SET-1)

Time: Three Hours                                                                 Max. Marks: 70

General Instructions 1. All questions are compulsory. 2. Question nos. 1 to 8 are very short answer questions and carry 1 mark each. 3. Question nos. 9 to 18 are short answer questions and carry 2 marks each. 4. Question nos. 19 to 27 are also short answer questions and carry 3 marks each. 5. Question nos. 28 to 30 are long answer questions and carry 5 marks each. 6. Use log tables if necessary, use of calculators is not allowed.

1.    Name the non- stoichiometric defect responsible for colour in alkali halides.

2.    A reaction is first order in A and second order in B. How is the rate affected when concentration of B is tripled?

3.    Give the IUPAC name of CH3CH(OH)CH2CH2CH2CH2CHO.

4.    A group 14 element is to be converted into n –type semi conductor by doping it with suitable impurity .To which group should this impurity belong?

5.    A reaction is first order in A and second order in B. How is the rate affected when the concentration of both A and B is doubled.

6.    Give the structure of : 5-Oxohexanoic acid.

7.    In the ring test for identification of nitrate ion, what is the formula of the compound responsible for the brown ring formed at the interface of two liquids?

8.    What type of bonding helps in stabilizing the  a-helix  structure of proteins.

9.    Aluminium crystallizes in a cubic close packed structure. Its’ metallic radius is 125 pm. (a) what is the length of the side of the unit cell.

(b) How many unit cells are there in 1cm3 of aluminium

10.    How do you account for molar conductivity of strong and weak electrolyte with concentration? Plot the graphs also.

11.    Explain the Electrophoresis with diagrams.

12.    (a) Name the catalyst and the promoter used in Haber’s process for

Manufacture of ammonia.

(b) Why is ferric chloride preferred over potassium chloride in case of a cut

Leading to bleeding?

13.(a) How is nitric acid obtained on large scale by Ostwald process?

(b) All the bonds in the molecules of PCl5 are not equal. Why


(a) H2S is less acidic than H2O.

(b) H2O is a liquid and H2S is a gas.

14.  Accomplish the following conversions:

(a)  Nitrobenzene to phenol (b)Methanamine to Ethanamine

15. (a) Fluorine exhibit oxidation state of –1 only whereas other halogens exhibit   +1, +3, +5, +7 oxidation states also.  .why

(b) Fluorine forms only one oxoacid, HOF

16. Give one chemical test to distinguish:

i.    Acetaldehyde and Benzaldehyde

ii.    Benzophenone and Acetophenone

17. Write the mechanism of nucleophilic addition reaction in aldehydes.

18. Give example for following name reaction:

i.    Reimer-Tiemann reaction

ii.    Kolbe’s reaction

19.(a) Conductivity of 0.00241M acetic acid is 7.896 X 10-6 S cm-1.  Calculate its molar conductivity. If ?0 for acetic acid is 390.5 S cm2 mol-1. What is its dissociation constant?

(b) When a current of 0.75A is passed through a CuSO4 solution for 25 min,   0.369g of copper is deposited at the Cathode. Calculate the atomic mass of copper.

20. (a) Write short notes on the following:  Order of reaction& Molecularity

(b) The rate of a reaction quadruples when the temperature changes from 293 K to 313 K. Calculate the energy of activation of the reaction assuming that it does not change with temperature.

21. (a) What is the role of depressant in froth flotation method?

(b) Giving chemical equations explain how leaching is used in metallurgy of silver .

22.(a) Does the hydrolysis of XeF6 lead to a redox reaction?

(c)Write the balanced equations involved in the preparation of PH3.

23. (a) Using IUPAC norms write the formulae for Dichlorido bis (ethane-1, 2-diamine) cobalt (III)

(b) Draw all the structures of optical isomers of  [CrCl(en)2(NH3)]2+

(c) Draw diagram to show splitting of d – orbital in octahedral crystal field

24. (a) Aldehydes are more reactive than Ketones towards Nucleophilic addition reaction

(b) There are two – NH2 group in semi carbazide however only one is involved in the formation of semi carbazones.

(c) During the preparation of esters from a carboxylic acid and an alcohol in the presence of an acid catalyst, the water or the ester should be removed as fast as it is formed.

25. (a) Name the deficiency diseases caused due to lack of vitamin  B6.

(b) Write the reactions when D-Glucose reacts with following: (i)HI(ii)ConcHNO3

26.  Write the structure of monomer& uses each of BunaN, Teflon, Bakelite.

27. Explain the following terms with suitable examples: (a) Cationic detergents (b) Anionic detergents (c) non-ionic detergents


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