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Public Model Question Paper Part-VII 2019 - 2020

12th Standard EM

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Chemistry

Time : 02:45:00 Hrs
Total Marks : 70

    Part I

    Answer all the questions.

    Choose the most suitable answer from the given four alternatives and write the option code with the corresponding answer.

    15 x 1 = 15
  1. Identify the metal that occurs in free state

    (a)

    Al

    (b)

    Au

    (c)

    Mg

    (d)

    Ca

  2. Which of the following statements is not correct?

    (a)

    Beryl is a cyclic silicate

    (b)

    Mg2SiO4 is an orthosilicate

    (c)

    SiO44−i the basic structural unit of silicates

    (d)

    Feldspar is not aluminosilicate

  3. The high reactivity of fluorine is due to_________

    (a)

    high ionisation energy

    (b)

    low bond dissociation energy

    (c)

    low electron affinity

    (d)

    high electro negativity

  4. Permanganate ion changes to ________ in acidic medium

    (a)

    MnO42−

    (b)

    Mn2+

    (c)

    Mn3+

    (d)

    MnO2

  5. Which one of the following complexes is not expected to exhibit isomerism?

    (a)

    [Ni(NH3)4(H2O)2]2+

    (b)

    <>

    (c)

    [Co(NH3)5SO4]Cl

    (d)

    [Fe(en)3]3+

  6. A regular three dimensional arrangement of identical points in space is called

    (a)

    Unit cell

    (b)

    Space lattice

    (c)

    Primitive

    (d)

    Crystallography

  7. For a first order reaction, the rate constant is 6.909 min-1.the time taken for 75% conversion in minutes is

    (a)

    \(\left( \cfrac { 3 }{ 2 } \right) { log }^{ 2 }\)

    (b)

    \(\left( \cfrac { 2 }{ 3 } \right) log2\)

    (c)

    \(\left( \cfrac { 3 }{ 2 } \right) log\left( \cfrac { 3 }{ 4 } \right) \)

    (d)

    \(\left( \cfrac { 2 }{ 3 } \right) log\left( \cfrac { 4 }{ 3 } \right) \)

  8. Using Gibb’s free energy change, ∆Go=57.34 kJ mol-1, for the reaction, X2Y(s)⇌2X++Y2- (aq), calculate the solubility product of X2Y in water at 300 K (R = 8.3 J K-1Mol-1)

    (a)

    10-10

    (b)

    10-12

    (c)

    10-14

    (d)

    can not be calculated from the given dat

  9. The conjugate base of NH-2 is

    (a)

    NH-

    (b)

    NH3

    (c)

    NH+3

    (d)

    NH2-

  10. The maximum work that can be derived from a chemical reaction is

    (a)

    Wmax = ΔH

    (b)

    Wmax = ΔG

    (c)

    Wmax = ΔE

    (d)

    Wmax = ΔS

  11. Adsorption of a gas on solid metal surface is spontaneous and exothermic, then

    (a)

    ΔH increases

    (b)

    ΔS increases

    (c)

    ΔG increases

    (d)

    ΔS decreases

  12. Oxidation of ethylene glycol with HIO4 gives _______

    (a)

    \(\overset { CHO }{ \underset { { CH }_{ 2 } }{ | } }\)

    (b)

    \(\overset { CH }{ \underset { CHO }{ | } } \)

    (c)

    \(\overset { COOH }{ \underset { COOH }{ | } } \)

    (d)

    HCHO

  13. Benzoic acid \(\overset { i){ NH }_{ 3 } }{ \underset { ii)\Delta }{ \longrightarrow } } A\overset { NaOBr }{ \longrightarrow } B\overset { NaN{ O }_{ 2 }/HCl }{ \longrightarrow } C\quad 'C'\quad is\)

    (a)

    anilinium chloride

    (b)

    O – nitro aniline

    (c)

    benzene diazonium chloride

    (d)

    m– nitro benzoic acid

  14. Nitro-acinitro tautomerism is exhibited by ____________

    (a)

    nitromethane

    (b)

    nitrobenzene

    (c)

    chloropicrin

    (d)

    o-toluidine

  15. ______act as a shock absorber and act lubricant.

    (a)

    glycogen

    (b)

    Ribose

    (c)

    starch

    (d)

    hyaluronate

  16. Part II

    Answer any 6 questions. Question no. 24 is compulsory.

    6 x 2 = 12
  17. What is calcination? Give example.

  18. What is catenation ? describe briefly the catenation property of carbon

  19. Give the reason for bleaching action of Cl2.

  20. Give an example for the complexes possessing co-ordination number 8 and 7

  21. Give any three characteristics of ionic crystals.

  22. Mention the factors that affected the rate of a chemical reaction.

  23. Account for the acidic nature of HClO4. In terms of Bronsted – Lowry theory, identify its conjugate base.

  24. Account for the following : For a strong electrolyte molar conductivity decreases as concentration increases

  25. Is it possible to oxidise t – butyl alcohol using acidified dichromate to form a carbonyl compound.

  26. Part III

    Answer any 6 questions. Question no. 33 is compulsory.

    6 x 3 = 18
  27. Write the complete set of reactions occurring in the zone of reduction in the blast furnace in the metallurgy of iron.

  28. Complete the following equations.
    (i) Cr2O72- + 2OH-
    (ii) MnO4- + 4H+ + 3e- ⟶

  29. What is salt bridge? How is it represented in a cell diagram?

  30. What happens when a colloidal sol of Fe(OH)3 and AS2O3 are mixed?

  31. Complete the following sequence of reaction and Identify A, Band C.

  32. An alkene (A) on ozonolysis gives propanone and aldehyde (B). When (B) is oxidised (C) is obtained. (C) is treated with BriP gives (D) which on hydrolysis gives (E). When propanone is treated with HCN followed by hydrolysis gives (E). Identify A) B) C) D and E.

  33. An organic compound 'A' on reduction gives compound 'B' which on reaction with trichloromethane and caustic potash forms 'C'. Compound 'C' on catalytic reduction given N-methyl benzenamine. Identify A, B and C and write the reactions involved.

  34. Give the sources of vitamin A and E and list the deficiency disease caused by lack of vitamin A and E in diet.

  35. How is Low density polyethene prepared?

  36. Part IV

    Answer all the questions.

    5 x 5 = 25
    1. How will you convert acetylene into n-butyl alcohol.

    2. How will acetic anhydride react with the following reagents?
      (i) HOH
      (ii) C2H5OH

    1. Will a precipitate be formed when 0.150 L of 0.1M Pb(NO3)2 and 0.100L of 0.2 M NaCl are mixed?\(K_{sp}\quad(PbCl_{2})=1.2\times10^{-5}\).

    2. Explain the various chemical methods by which colloids can be prepared.

    1. Ionic solids, which have anionic vacancies due to metal excess defect, develop colour. Explain with the help of a suitable example.

    2. From the following data, show that the decomposition of hydrogen peroxide is a reaction of the first order:

      t(min) 0 10 20
      V(ml) 46.1 29.8 19.3

      Where t is the time in minutes and V is the volume of standard KMnO4 solution required for titrating the same volume of the reaction mixture.

    1. Write a short note on the oxidation states of 3d series elements.

    2. What is meant by stability of a co-ordination compound in solution? State the factors which govern stability of complexes.

    1. 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.

    2. An element 'A' occupies group number 15 and period number 3. It reacts with chlorine: to giveBwhich further reacts with chlorine to giveCat 273K. Both Band Care chlorinating agents for organic compounds. C is a better chlorinating agent because it chlorinates metals also.Breacts with SO3and reduces it to SO2' B has a pyramidal shape. C has
      trigonal bipyramidal shape by sp3d hybridisation. Identify the element A and the compounds B ' and C. Write the reactions.

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