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12th Standard Chemistry English Medium P - Block Elements - I Reduced Syllabus Important Questions 2021

12th Standard

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 100

    Multiple Choice Questions

    15 x 1 = 15
  1. Boric acid is an acid because its molecule 

    (a)

    contains replaceable H+ ion

    (b)

    gives up a proton

    (c)

    combines with proton to form water molecule

    (d)

    accepts OH- from water ,releasing proton.

  2. In diborane, the number of electrons that accounts for banana bonds is

    (a)

    six

    (b)

    two

    (c)

    four

    (d)

    three

  3. Carbon atoms in fullerene with formula C60 have

    (a)

    sp3 hybridised

    (b)

    sp hybridised

    (c)

    sp2 hybridised

    (d)

    partially sp2 and partially sp3 hybridised

  4. Oxidation state of carbon in its hydrides

    (a)

    +4

    (b)

    -4

    (c)

    +3

    (d)

    +2

  5. The repeating unit in silicone is v

    (a)

    SiO2

    (b)

    (c)

    (d)

  6. Which of the following is not sp2 hybridised?

    (a)

    Graphite

    (b)

    graphene

    (c)

    Fullerene

    (d)

    dry ice

  7.   Column-I     Column-II
    A Borazole 1 B(OH)3
    B Boric acid 2 B3N3H6
    C Quartz 3 Na2[B4O5(OH)4]8H2O
    D Borax 4 SiO2
    (a)
    A B C D
    2 1 4 3
    (b)
    A B C D
    1 2 4 3
    (c)
    A B C D
    1 2 4 3
    (d)

    None of these

  8. The compound that is used in nuclear reactors as protective shields and control rods is

    (a)

    Metal borides

    (b)

    metal oxides

    (c)

    Metal carbonates d) metal carbide

    (d)

    none of these

  9. The stability of +1 oxidation state increases in the sequence

    (a)

    Al < Ga < In < Tl

    (b)

    Tl < In < Ga < Al

    (c)

    In < Tl < Ga < Al

    (d)

    Ga< In < Al < Tl

  10. The stability of +1 oxidation state among Al, Ga, In and Tl increases in sequence

    (a)

    TI < In < Ga < Al

    (b)

    In < TI < Ga < Al

    (c)

    Ga < In < Al < TI

    (d)

    Al < Ga < In < TI

  11. SiO44- ion has ____ geometry.

    (a)

    Triangular

    (b)

    Tetrahedral

    (c)

    Linear

    (d)

    Pentagonal bipyramidal

  12. Which of the following statements about H3BO3 is not correct?

    (a)

    It has a layer structure in which planar BO3 units are joined by H-bonds

    (b)

    It is a strong tribasic acid

    (c)

    It is prepared by acidifying an aqueous solution of borax

    (d)

    It does not act as proton donor but acts as lewis acid by accepting hydroxyl ion

  13. Elements of group 13 mainly form covalent compounds because ______

    (a)

    small size

    (b)

    electro negativity values are high

    (c)

    ionization energy is very high

    (d)

    both (a) and (c)

  14. Allotropy is due to ______

    (a)

    difference in chemical properties

    (b)

    difference in the number of atoms in the molecules

    (c)

    difference in the arrangement of atoms in the molecules in the crystal

    (d)

    None of these

  15. The silicates which contain discrete tetrahedral units are _______

    (a)

    ortho silicates

    (b)

    sheet silicates

    (c)

    pyrosilicates

    (d)

    three dimensional silicates

  16. 2 Marks

    10 x 2 = 20
  17. Write a short note on anamolous properties of the first element of p-block

  18. Give the uses of Borax

  19. Write a note on Fisher tropsch synthesis

  20. Give the structure of CO and CO2.

  21. What are alums?

  22. Give the uses of alum.

  23. What is oxo process?

  24. What is tetraethoxy silane? How is it obtained?

  25. What are silicones?

  26. Name the building block of zeolites. Why zeolites have high porosity?

  27. 3 Marks

    10 x 3 = 30
  28. Give the uses of silicones

  29. Describe the structure of diborane

  30. Write a note on metallic nature of p-block elements

  31. Draw the structure of boric acid.

  32. What happens to boranes at high temperatures?

  33. What are the uses of diborane?

  34. Describe the structure of fullerenes.

  35. Describe the structure of graphene.

  36. How is CO2 manufactured?

  37. Account for the following:
    (i) CO is used in the extraction of metals.
    (ii) CO is poisonous
    (iii) CO2 is used in referigeration

  38. 5 Marks

    7 x 5 = 35
  39. How will you identify borate radical?

  40. How will you convert boric acid to boron nitride?

  41. A hydride of 2nd period alkali metal (A) on reaction with compound of Boron (B) to give a reducing agent (C). identify A , B and C.

  42. A double salt which contains fourth period alkali metal (A) on heating at 500K gives (B). aqueous solution of (B) gives white precipitate with BaCl2 and gives a red colour compound with alizarin. Identify A and B.

  43. CO is a reducing agent . justify with an example.

  44. What are the various methods by which carbon-di-oxide is prepared?

  45. Distinguish between diamond and graphite.

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