CBSE Guess > Papers > Question Papers > Class XII > 2003 > Chemistry > Compartment Delhi Set -I.

CHEMISTRY—2003 (Set I—Compartment Delhi)

Q. 2. What is the possible value of angular momentum quantum number (1) for the unpaired electron in the atom of an element whose atomic number is 17? 1

Q. 3. In an alloy of gold and cadmium, gold crystallizes in cubic structure occupying the corners only and cadmium fits into the face centre voids. What is the quantitative composition of the alloy? 1

Q. 4. What will happen when red blood cells are placed in water? 1

Q. 5. Which solution will allow greater conductance of electricity, I M NaCI at 293 K or 1 M NaCl at 323 K? 1

Q. 6. Give one important industrial use of phenyl isocyanide. 1

Q. 7. Why is hydrogen sulphide, with greater molar mass, a gas, while water a liquid at room temperature?1

Q. 8. Mention two uses of pyrophoric alloys. 1

Q. 9. How does the addition of alum purify water? 1

Q. 10. What is 'codon'? 1

Q. 11. Write the de-Broglie education and establish a relation between wavelength of a moving subatomic particle and its kinetic energy. 2

Q. 12. An element occurs in BCC structure with cell edge of 300 pm. The density of the element is S. g cm ^-3 How many atoms of the element does 200 g of the element contain? 2

Q. 13. An aqueous solution of sodium chloride freezes below 273 K. Explain the lowering in freezing point of water with the help of a suitable diagram. 2

Q. 14. Calculate the volume of 80% (by mass) of H₂ SO₄ (density = 1.80 g/ml) required to prepare 1 litre of 0.2 molar H ₂SO₄ (Relative atomic masses: H = 1,O = 16, S = 32) 2

Q. 15. Evaporation of water is an endothermic process but spontaneous. Explain. 2

Q. 16. Explain the mechanism of chemical reaction between H ₂ and Cl ₂ in the presence of sunlight. Write any two important observations on such reactions.2

Q. 17. What will be the initial rate of reaction if its rate constant is 10 ^-3 s ^-1 and the concentration of the reactant is 0.2 mol L ^-1 ? What fraction of the reactant will be converted into the products in 200 seconds? 2

Q. 18. Account for the following:

(a) o-nitrophenol has lower boiling point than p-nitro-phenol.
(b) The dipole moment of chlorobenzene is less than that of methyl chloride.

Q. 19. Write the IUPAC names for the following: 2
(i)

(ii) CH3 - CH2 - CH - COOH
                                |
                               Br

Q. 20. In contrast to arenes, aliphatic hydrocarbons do not undergo nitration. Explain. 2

Q. 21. Give chemical tests to distinguish between the following pairs of compounds:
(a) 1-nitropropane an 2-nitripropane 2
(b) CH ₃ - CH ₂ - NH ₂ and (CH ₃ ) ₂ NH

Q. 22. How do the thermoplastic polymers differ from thermosetting polymers in their mode of formation? Give one example of each. 2

Q. 23. Why do lyophilic sols not require any stabilizing agent for their preservation? How is colloidal sulphur in water prepared? 2

Q. 24. What is 'genetic engineering'? Mention two of its main objectives. 2

Q. 25. Answer the following: 2
(a) How does respiration impart colour to blood?
(b) How do cells derive their need of ATP?

Q. 26. Give three examples of sulpha drugs and write their main uses. 2

Q. 27. (a) Illustrate with an example what is meant by standard enthalpy of formation of a compound.
(b) State the relation between standard free energy change and equilibrium constant of a chemical reaction.
⁰C for the process

Calculate the value of

Q.28. The emf of the cell has been found to be 0.305 V at 298 K. Calculate the value of M ₁ .

Q. 29. How will you obtain the following:
(a) 1, 2etkaaedlol from ethanol
(b) 2-metIi from 2
(c) Benzoic acid from chlorbenzene
Give the complete chemical reaction and condition in each case.

Q. 30. What happens when (write reactions only): 3
(a) Methoxybenzene Is subjected to nitration.
(b) Ethanamide is reacted with HNO₂.
(c) Acetic acid is reacted with chlorine in the presence of red phosphorus.

Q. 31. (a) A coordination compound has the formula CoCI ₃ . 4NH ₃ . It does not liberate ammonia but forms a precipitate with AgNO ₃ . Write the structure and IUPAC name of the complex compound.
(b) Name a ligand. Which is bidentate and give an example of the complex formed by this ligand. 3

Q. 32. (a) State the principle of 'neutron activation analysis'.
(b) A sample of U-238 (half -life 4.5 x 10⁹ years) ore is found to contain 23.8 g of U-238 and 20.6 g of Pb-206. Calculate the age of the ore. 3

Q. 33. Explain the following observations: 5
(a) Hydrogen fluoride has the highest boiling point among th hydrogen halides.
(b) Although I.E. of lithium is maximum amongst Group 1 metals, it is the Strongest reducing agent in solution.
(c) Sodium metal can be used for drying ether but cannot be used for drying
(d) A nitrogen atom has five valence electrons but it does not form the compound NCI 5 .
(e) Solubility of sulphates of Group 2 elements in water decreases down the group.

Q. 34. (a) Explain the following:
(i) The transition elements have high enthalpies of atomization.
(ii) The d-block elements exhibit more number of oxidation states than do the f-block elements.
(b) A green chromium compound 'A' on fusion with alkali gives a yellow compound 'B' which on acidification gives an orange coloured solution 'C'. 'C' on treatment with NH4 CI gives a coloured product 'D' which on crystallization and subsequent heating decomposes to give back compound 'A' identify A, B, C and D. Write equations for the reactions involved. 5

Chemistry 2003 Question Papers Class XII
Delhi		Outside Delhi		Compartment Delhi		Compartment Outside Delhi
	Set I		Set I		Set I		Set I
	Set II		Set II		Set II		Set II