Thursday, December 27, 2007

Time: Three Hours Max. Marks: 70

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

1. A reaction is 2A + B 2D and rate law is found to be Rate = k [A]3/2 What is order and molecularity of reaction? (1)
2. H3PO3 is diprotic. Why? (1)
3. How many moles of vacant cationic sites will be there if NaCl crystal is doped with 2x10-10 mole Indium Chloride? (1)
4. For the following reaction, 4NH3 (g) + 5O2 (g) 4NO (g) + 6H2O (g) . write the rate of formation of ‘NO’ in terms of concentration of ammonia. (1)
5. Write IUPAC name of compound CH3 NH CH3 (1)

6. Write the co-ordination number of Ca 2+ and F – ions in ionic solid CaF2.
7. Arrange the following halides in order of increasing reactivity through SN2 mechanism. (1)
CH3CH2Br, CH3Br, (CH3)3CBr, (CH3)2CHBr.
8. Write the change that occurs in the structure of protein when raw egg is boiled. (1)
9. What will be the effect of temperature on the adsorption of a gas on solid in case of physisorption and chemisorption? (2)
10. What happens when (2)
I. Electric current is passed through ferric hydroxide sol.
II. Freshly prepared precipitate of AgCl is agitated with aqueous solution of silver nitrate.
11. An element (density 6.8 g cm-3) occurs in BCC structure with cell edge of 280 pm. Calculate the number of atoms presents in 250 gm of element. (2)
12. The graphical representation of the variation of m vs. for two electrolytes AB and PQ was found as below (2)



I. Write the nature of electrolytes AB and PQ.
II. Write the effect of dilution on the dissociation of AB.
13. Write the chemical reactions in which sulphuric acid acts as (2)
I. Dehydrating agent
II. Oxidizing agent
14. Why is o-nitro phenol more acidic than phenol but less acidic than p-nitro phenol? Explain. (2)
15. Write the mechanism of formation of diethyl ether from ethanol.
Write Williamson’s synthesis process for preparation of methoxy ethane? Write one important advantage of this method.
16. How will you distinguish between (2)
I. Benzyl amine and aniline.
II. Secondary amine and tertiary amine.
17. A colourless crystalline solid C7H6O2 on heating with PCl5 gives a compound ‘A’ which on Rosenmund reduction gives a compound ‘B’. Further oxidation of ‘B’ gives out original crystalline solid. (2)
a) Identify A and B.
b) Write the chemical reactions involved in the formation of A and B.
18. Arrange the following compounds in the increasing order of property indicated. (2)
a) HBr, HF, HCl, HI (acidic strength).
b) HClO3, HClO, HClO4, HClO2 (stability).

19. Write the chemical reaction that occurs during (3)
I. Preparation of Al by electrolytic reduction of Alumina.
II. Refining of Nickel by Mond’s process.
III. Extraction of Ag by leaching with NaCN.
20. How is Xenon hexafluoride prepared? Draw its structure and write the type of hybridization. (3)
21. Explain the following citing one example (3) . I. 1. Analgesics
I. 2.Broad spectrum antibiotics
II. 3. Anti histamines

What are antimicrobials? Give one example. Write the three ways of controlling a microbial disease.
22. (a) What is Lanthanide contraction? Write its two consequences. (2)
(b) Transition metals form coloured compounds. Why? (1)
23. What are fuel cells? Write the reaction taking place at anode and cathode in Hydrogen-oxygen fuel cell with brief explanation. (3)
24. The following experimental data was collected for the reaction at 298K . (3)
Cl2 (g) +2NO (g) 2NOCl (g)

21.6 x 10-4
a) Write the rate law for above reaction.
b) Determine the rate constant.
c) Calculate the rate of reaction when concentration of Cl2 (g) and NO (g) are 0.015 and 0.025 mol l-1 respectively.
25. (a) Write the names of two components of starch. How do they differ in (3)
I. Structural unit.
II. Solubility in water
Explain the following in case of DNA
I. Mutation
II. Replication (iii) Transcription

26. (a) What are co-polymers? Give one example. (1)
(b) How is PVC manufactured? What is the role of benzoyl peroxide in polymerization of vinyl chloride? (2)
27. How will you convert (3)
I. Isopropyl chloride into propene
II. Phenol into o-bromophenol
III. Aniline into benzoic acid.
28. (a) What is Henry’s Law? Write its two limitations. (2)
(b) What is osmosis? Average osmotic pressure of human blood is 7.4 atm at 270C. Calculate total concentration of various solutes present in the blood. Assuming this concentration in molality, calculate the freezing point of blood.
(Kf =1.86 Kg molal-1, R =0.0821 l atm K-1 mol-1) (3)
a) What is abnormal molecular mass? Write the value of Vant Hoff factor for benzoic acid dissolved in benzene. (2)
b) Two liquids X and Y on mixing form ideal solution. The vapour pressure of solution containing 3 mol of X and 1 mol of Y is 550 mm of Hg. But when 4 mol of X and 1 mol of Y are mixed the vapour pressure is 560 mm of Hg. Calculate the vapour pressure of pure X and Y. (3)
29. (a) Account for the following (2)
I. Chloro acetic acid is stronger than acetic acid.
II. Ethanamide has higher boiling point than ethanoic acid.
III. Aniline does not undergo Friedal and Craft reaction.
(b) Write IUPAC name of following (3)
I. (CH3)3 C-CHCl-CH3

30. (a) What are geometrical isomers? Represent the geometrical isomer of
Co (en)2Cl2 + ion. (2)
(b) Out of two complexes Fe (CN)6 3-and Fe(CN)6 4- which one is more stable and why ? (1)
(c) Give reasons (1+1)
I. Ce4+ ion is more stable than Ce2+.
II. KMnO4 solution is decolourised by acidified solution of oxalic acid.

A series of organic reaction is represented as below. (2+2+1)
A Conc HNO3 +H2SO4 B Sn/HCl C NaNO2 + HCl D HOH
278 K Boil
a) Identify A, B, C and D.
b) Write the complete chemical reaction for each step.
c) Write the type of reaction changing C into D.

Prepared and presented by:-
C.D. Ram, Vice Principal
K.V. OEF Hazratpur

Sample Questions for Low Achievers(BIO)

Class: XII
Sub: Biology
Sample Questions for Low Achievers
Dr Neeta Singh PGT BIO
UNIT-IV 2Marks Questions

1. Explain any two methods of vectorless gene transfer.
2. What is a palindromic sequence on DNA? Why is it useful in recombinant DNA technology?
3. What are restriction enzymes? Name and describe their two major kinds.
4. Name the technique used for separation of DNA fragments. What is its principle?
5. How is Agrobacterium tumefaciens used as a vector for transformation of plant cells?
6. Mention the key tools necessary for rDNA technology.
7. What is genetic engineering? List the steps involved in rDNA technology.
8. What is Ti plasmid?Name the organism where it is found?How does it help in genetic engineering?
9. What are genetically modified organisms? Give examples of one plant and one animal.
10. What are the advantages of molecular diagnostics over conventional methods?
11. What are Cry proteins? Name an organism that produces it. How has man exploited this protein to his benefit?
12. Expand PCR. How is it useful in biotechnology?
13. Name the following-
(a). The first transgenic cow
(b). The substance used as medium in gel electrophoresis
(c). The enzyme used to digest cell wall of bacteria
(d). The enzyme characteristic of retroviruses.
14. What is a cloning vector? Explain the technique of using such a vector in E. coli.
15. Compare and contrast the advantage and disadvantages of production of GM crops.
16. What are the disadvantages of insulin from animal sources. What are the concerns about transgenic insulin?
17. What is gene therapy? Illustrate using the example of ADA deficiency.
18. Expand PCR. What is its use in diagnostics?
19. Define biopiracy. What are the concerns about Neem and Turmeric?
20. Mention any six fields of application of biotechnology in human welfare.

-Dr Neeta Singh PGT BIO

Saturday, December 22, 2007

SAMPLE PAPER-Class: XII Sub: Biology


Instructions: As usual

The discovery of an enzyme revolutionized the field of genetic engineering and changed the central dogma of molecular biology in 1975. Name the enzyme and the reaction catalyzed by it?
Name the process of rupture of Graffian follicle and the subsequent release of egg from the ovary.
What name is given to the type of growth that assumes a sigmoid curve?
Which type of immunity is provided by vaccination?
Mention the two key concepts of Darwinism?
What do the oral contraceptive pills contain?
How is maize plant adapted for anemophily?
Name the two richest zones of biodiversity in India.


9. What are sacred groves? What is their role in conservation of biodiversity?
10. How is phosphorus cycle different from carbon cycle?
11. The gene for Hemophilia doesn’t pass from father to son or from mother to daughter. Name the type of inheritance and explain the mechanism.
12. What is the processing of hnRNA? Why is it necessary in eukaryotes?
13. Name the two types of cells present in the inner lining of seminiferous tubule. What are their functions?
14. What are the drawbacks of conventional insulin? How does transgenic insulin overcome these?
15. What is tapetum? What is its role in the developing anther?
16. Workout the possible genotypes and phenotypes in the offspring produced in a cross between a red flowered (homozygous) and a white flowered (homozygous) 4O’clock plant. Name the type of inheritance shown by the cross.
17. What are the characteristics of acquired immunity? Which of these is exploited in vaccination?
The base sequence on one of the strands of DNA is-
(a). Write the base sequence of its complementary strand.
(b). What will be the sequence of mRNA transcribed on it?
18. Name the labeled parts of the given diagram.


19. What are Cry proteins? Name an organism that produces them. How is it being used in
crop protection?
20. What are the exceptions of Mendel’s law of Independent assortment? Why were these
not detected by Mendel?
21. Bring out the salient features of Genetic code. Why is the code said to be degenerate?
(a). What are methanogens?
(b). How are biofertilizers more advantageous over traditional fertilizers?
23. How can one prove Darvinian theory of Natural selection true by putting forward an
example? Explain.
24.What are statins? Where are they produced? How are they useful to man?
25. What is corpus luteum? Mention its role as an endocrine gland?
26.What are the activities included in ex situ strategies of conservation of biodiversity?
27. How are the autoimmune diseases different from immunodeficiency diseases? Give
examples of each.
What are interferons? Which type of immunity do they provided? Explain.


28. Where do the transcription and translation occur in a cell? Explain the process of
translation in eukaryotic cell.

What is Lac oparon? How is the operator switched on or off in the expression of genes in
this oparon?
29. (a).What are algal blooms? How are they formed?Give two harm ful effects of it in a
water body.
(b). Why does biomagnification occur with some substances? Give example
(a).What is Jhum cultivation? Explain how it is responsible for deforestation.
Describe organic farming.
Name the most common method of removal of particulate air pollutants.
30.(a) Why is autogamy discouraged in plants? Memtion any four adaptations to ensure xenogamy.
(b).Draw a labeled diagram of V.S. of a maize grain.
Where and when does oogenesis take place in human female? Describe the events of female reproductive cycle.


Sunday, December 16, 2007

The KVS Merry Go Round

[On KVS Foundation Day]

By Smt S Datt
TGT English

It’s March 31st
The result is out>
Faces change colour
Whether lean or stout

New books to be bought
Notebooks to be covered
The first test is round the corner
The days are numbered

The only ray of hope is the summer vacation
To come back afresh to continue the session
Thus trigger off the activities
The supplementaries
The parents’ pleas
And not to forget the collection of fees
Classwork and homework that can’t be shirked
Classes that can’t be missed
You are still busy with admissions
But its time for Inter House Competitions
Science and Social Science Exhibitions
Sudden Inspections
The PTA and Staff Meetings
The indispensable Remedial sittings
The Regionals and Nationals
The celebration of festivals

The Teaching Testing and Checking
Ensure that nothing is lacking
You raise your head one day and see
Its January
Its not all over yet
The exam papers have to be set
The assessment is yet to be done
Errors there should be none
For which to school the children are sent
But inspite of all the drudgery and din
A KV is a wonderful place to be in