CBSE 12th Board Sample Paper IV Chemistry


Sample papers


Central Board of Secondary Education (CBSE)

Sample Paper – 2012
Class – XII
Subject – C
hemistry




 


  1. What causes Brownian movement in a colloidal solution?
  2. Write the IUPAC name of the following organic compound. CH3-O-CH2-CH(OH)-CH2-CH3
  3. Arrange the following compounds in an increasing order of acidic strengths: CH3CH2CH(Br)COOH,               CH3CH(Br)CH2COOH, (CH3)2CHCOOH, CH3CH2CH2COOH.
  4. Write chemical equation when PtF6 and xenon are mixed together.
  5. What is the use of SO2 formed during the roasting of sulphide ores?
  6. Mention a large scale use of the phenomenon called reverse osmosis?
  7. Write an example of a neutral molecule which is isoelectronic with ClO.
  8. Write structural formula of 2,3-dichloropentane. State whether it is optically active or not.
    1. State Raoult’s law for solutions of two volatile liquids. Taking suitable examples explain the meaning of positive and negative deviation from Raoult’s law.

10. Calculate the amount of KCl which must be added to 100g of water so that water freezes at -2.0oC.Assume that KCl undergoes complete dissociation.

11. Distinguish between order and molecularity of a reaction. When could order and molecularity of a reaction be the same?

12. Outline the principles of the following:

(i)   Zone refining

(ii)  Paper chromatography.

13. State the difference between Schottky and Frenkel defects. Which of the two changes the density of the solid?

14. Analysis shows that nickel oxide has formula Ni0.96O1.00. What fractions of nickel exist as Ni2+ and Ni3+ ions?

15. What happens when D-Glucose is treated with the following reagents?

(i)   HI

(ii)  Bromine water.

16. Answer the following:

(i)   What type of linkage is responsible for the primary structure of proteins?

(ii)  What are any two good sources of vitamin ‘A’?

17. Explain the difference between:

(a) Aniline and Ethylamine

(b) dimethylamine and Methylamine

18. Account for the following:

(i)   Aniline does not undergo friedel-crafts reaction.

(ii)  Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.

19. Define the following with a suitable example.

(a) Coupling reaction.

(b) Reimer-Tiemann reaction.

(c)Williamson synthesis.

20. (a) Why aryl halides are extremely less reactive towards nucleophilic substitution reaction?

(b) In the following pairs of halogens compounds, which compound undergoes faster SN1 reaction?

21. The following data were obtained during the first order thermal decomposition of SO2Cl2at constant volume.

SO2Cl2(g)→SO2(g)+Cl2(g)

Experiment

Time/s

Total pressure/atm

1

0

0.5

2

100

0.6



22. Write short notes on the following:Calculate the rate of the reaction when total pressure is 0.65 atm.

(a) Froth Floatation process.

(b) Cataphoresis.

(c) Zeta potential.

23. Complete the following chemical equations:

(i)   XeF2+PF5

(ii) HgCl2 +PH3

(iii)     P4+NaOH+H2O→.

24. Account for the following:

(i)   NH3 is stronger base than PH3.

(ii)  The electron gain enthalpy with negative sign for oxygen is less than that of sulphur.

(iii)      H3PO2 and H3PO3 act as good reducing agent while H3PO4 does not.

25. Indicate the type of isomerism exhibited by the following complexes and draw the structures for these isomers:

(i)   [Co (en)2Cl2]

(ii)  [Co(NH3)3(NO2)3]

(iii)     [Co(en)3]Cl3.

26. (a) Differentiate between the thermoplastic and thermosetting polymers.

(b) What are biodegradable polymers? Give two examples.

27. State the function along with one example each of:

(i)   Antihistamines

(ii)  Antioxidants

(iii)     Tranquilizers.

28. (a) State two advantages of H2-O2 fuel cell over ordinary cell.

(b) A copper-silver cell is set up. The copper ion concentration in it is 0.10M. The concentration of silver ion is not known. The cell potential measured is 0.422V. Determine the concentration of silver ion the cell.

(Given: Eo Cu2+/Cu=+0.34V and EoAg+/Ag=+0.80V)

29. (a) Write the steps involved in the preparation of:

(i)   K2Cr2O7 from Na2CrO4.

(ii)  KMnO4 from K2MnO4.

(b) What is meant lanthanoid contraction? What effect does it have on the chemistry of the elements which follow lanthanoids?

30. (a)Define your view about following conversions in more than two steps? (i) Propanone to Propene (ii)       Benzoic acid to Benzaldehyde.

(b) An organic compound ‘A’ contains 69.77% carbon, 11.63% hydrogen and the rest is oxygen. The molecular mass of ‘A’ is 86. It does not reduce Tollen’s reagent but forms an addition compound with sodium hydrogen sulphite. ‘A’ gives a positive iodoform test. On vigorous oxidation ‘A’ gives ethanoic and propanoic acids. Deduce the possible structure of molecule of ‘A’.

Sample Paper / Model Test Paper CBSE 12th 2012



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