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p - Block Elements - I Model Question Paper

12th Standard

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 45
    8 x 1 = 8
  1. Oxidation state of carbon in its hydrides _______.

    (a)

    +4

    (b)

    -4

    (c)

    +3

    (d)

    +2

  2. The geometry at which carbon atom in diamond are bonded to each other is _______.

    (a)

    Tetrahedral

    (b)

    hexagonal

    (c)

    Octahedral

    (d)

    none of these

  3. AlF3 is soluble in HF only in the presence of KF. It is due to the formation of _________.

    (a)

    K3[AIF3H3]

    (b)

    K3[AiF6]

    (c)

    AIH3

    (d)

    K[AIF3H]

  4. Thermodynamically the most stable form of carbon is________.

    (a)

    Diamond

    (b)

    graphite

    (c)

    Fullerene

    (d)

    none of these

  5. Chemical formula of phosgene is_______.

    (a)

    COCl2

    (b)

    CaOCl2

    (c)

    CaCO3

    (d)

    COCI

  6. 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

  7. Oxidation state exhibited by group 13 elements is ______

    (a)

    +1, +2 and +3

    (b)

    +1 and +3

    (c)

    +1 and +4

    (d)

    +2 +3 and +4

  8. 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

  9. 2 x 1 = 2
  10. I. Boric acid can be extracted from borax and colemanite.
    II. Boric acid is a colourful crystal.
    III. It is a very weak monobasic acid.
    IV. It accepts hydroxyl ion rather than donating proton.
    a) Only I
    b) Only II
    c) I, III & IV
    d) III & IV

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    I, III & IV

  11. I. Graphene is an allotropic from of carbon
    II. CO is a strong reducing agent
    III. CO is a poisonous gas.
    IV. CO is used as a propellent
    a) I, II & III
    b) Only II
    c) Only I
    d) III & IV

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    I, II & III

  12. 2 x 2 = 4
  13. Assertion: When borax is strongly heated it forms transparent glassy bead.
    Reason: Borax is the other name for sodium tetraborate decahydrate.
    Codes:
    a) Both assertion and reason are true and the reason is the correct explanation of the assertion.
    b) Both the assertion and reason are true but the reason is not the correct explanation of the assertion.
    c) Assertion is true but reason is false.
    d) Both assertion and reason are false.

  14. Assertion: Carbon shows an anomalous behaviour in group 14.
    Reason: Carbon has maximum covalency of 4.
    Codes:
    a) Both assertion and reason are true and the reason is the correct explanation of the assertion.
    b) Both the assertion and reason are true but the reason is not the correct explanation of the assertion.
    c) Assertion is true but reason is false.
    d) Both assertion and reason are false.

  15. 2 x 2 = 4
  16. a) Alum is potassium aluminium sulphate
    b) Alum is extracted from colemanite
    c) Anhydrous aluminium chloride a catalyst in Friedels crafts reactions.
    d) Its a Lewis acid

  17. a) Carbon is found in the native form as graphite.
    b) Coal contains large quantities of carbon
    c) Clay is important source for carbon.
    d) Carbon exists in many allotropic forms.

  18. 4 x 2 = 8
  19. Boron does not react directly with hydrogen. Suggest one method to prepare diborane from BF3.

  20. What is phosgene? How is it prepared?

  21. Name the two important ores of Boron.

  22. Starting from SiCl4, prepare the following in steps not exceeding the number given in parentheses.
    (i) Silicon
    (ii) Linear silicon containing methyl groups only
    (iii) Na2SiO3

  23. 3 x 3 = 9
  24. Describe the structure of diborane.

  25. How is boron trifluoride obtained from boron trioxide?

  26. Describe the structure of diamond.

  27. 2 x 5 = 10
  28. Write a note on zeolites.

  29. Distinguish between diamond and graphite.

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