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12th Standard Chemistry English Medium Reduced Syllabus Important Questions with Answer key - 2021 Part - 2

12th Standard

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Chemistry

Time : 02:45:00 Hrs
Total Marks : 165
    Multiple Choice Questions
    15 x 1 = 15
  1. Which one of the following reaction represents calcinations?

    (a)

    \(2Zn+{ O }_{ 2 }\rightarrow 2ZnO\)

    (b)

    \(2ZnS+3O_{ 2 }\rightarrow 2ZnS+3O_{ 2 }\rightarrow 2ZnO_{ 2 }\rightarrow 2ZnO+2SO_{ 2 }\)

    (c)

    \(MgCO_{ 3 }\rightarrow MgO+CO_{ 2 }\)

    (d)

    Both (a) and (c)

  2. Electrochemical process is used to extract

    (a)

    Iron

    (b)

    Lead

    (c)

    Sodium

    (d)

    silver

  3. Extraction of gold and silver involves leaching with cyanide ion. silver is later recovered by (NEET-2017)

    (a)

    Distillation

    (b)

    Zone refining

    (c)

    Displacement with zinc

    (d)

    liquation

  4. In the Ellingham diagram, for the formation of carbon monoxide

    (a)

    \(\left( \cfrac { \Delta { S }^{ 0 } }{ \Delta T } \right) \)

    (b)

    \(\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right) \) is positive

    (c)

    \(\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right) \) is negative

    (d)

    initially \(\left( \cfrac { \Delta T }{ \Delta { G }^{ 0 } } \right) \) is positive, after 700oC,\(\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right) \) is negative

  5. \({ Zn }_{ (s) }+2\left[ Au(CN)_{ 2 } \right] ^{ - }_{ (aq) }\longrightarrow \left[ Zn(CN)_{ 4 } \right] ^{ 2- }_{ (aq) }+2Au{ { u }_{ (s) } }\) In the above equation) the oxidation state of metallic;gold is_______

    (a)

    1

    (b)

    0

    (c)

    +2

    (d)

    -2

  6. Which of the following metals has the largest abundance in the earth’s crust?

    (a)

    Aluminium

    (b)

    calcium

    (c)

    Magnesium

    (d)

    sodium

  7. The repeating unit in silicone is v

    (a)

    SiO2

    (b)

    (c)

    (d)

  8. Most easily liquefiable gas is

    (a)

    Ar

    (b)

    Ne

    (c)

    He

    (d)

    Kr

  9. On oxidation with iodine, sulphite ion is transformed to

    (a)

    S4O62-

    (b)

    S2O62-

    (c)

    SO42-

    (d)

    SO32-

  10. Assertion : monoclinic sulphur is an example of monoclinic crystal system
    Reason: for a monoclinic system, \(a\neq b\neq c\) and \(\alpha =\gamma ={ 90 }^{ 0 },\beta \neq { 90 }^{ 0 }\) 
    Codes:
    (a) Both assertion and reason are true and reason is the correct explanation of assertion
    (b) Both assertion and reason are true but reason is not the correct explanation of assertion.
    (c) Assertion is true but reason is false.
    (d) Both assertion and reason are false.

    (a)

    Both assertion and reason are true and reason is the correct explanation of assertion

    (b)

    Both assertion and reason are true but reason is not the correct explanation of assertion.

    (c)

    Assertion is true but reason is false.

    (d)

    Both assertion and reason are false.

  11. if ‘a’ is the length of the side of the cube, the distance between the body centered atom and one corner atom in the cube will be

    (a)

    \(\left( \cfrac { 2 }{ \sqrt { 3 } } \right) a\)

    (b)

    \(\left( \cfrac { 4 }{ \sqrt { 3 } } \right) a\)

    (c)

    \(\left( \cfrac { \sqrt { 3 } }{ 4 } \right) a\)

    (d)

    \(\left( \cfrac { \sqrt { 3 } }{ 2 } \right) a\)

  12. A two dimensional solid pattern formed by two different atoms X and Y is shown below. The black and white squares represent atoms X and Y respectively. the simplest formula for the compound based on the unit cell from the pattern is

    (a)

    XY8

    (b)

    X4Y9

    (c)

    XY2

    (d)

    XY4

  13. Equal volumes of three acid solutions of pH 1,2 and 3 are mixed in a vessel. What will be the H+ ion concentration in the mixture?

    (a)

    3.7 ×10-2

    (b)

    10-6

    (c)

    0.111

    (d)

    none of these

  14. Electrolyte KCl KNO3 HCl NaOAC NaCl
    Λ-
    (Scm2 mol-1)
    149.9 145.0 426.2 91.0 126.5

    Calculate ΛoHoAC using appropriate molar conductances of the electrolytes listed above at infinite dilution in water at 25oC.

    (a)

    517.2

    (b)

    552.7

    (c)

    390.7

    (d)

    217.5

  15. In the reaction sequence, Ethane \(\overset { HOCl }{ \longrightarrow } A\overset { x }{ \longrightarrow } \) ethan -1, 2 - diol . A and X respectively are

    (a)

    Chloroethane and NaOH

    (b)

    ethanol and H2SO4

    (c)

    2 – chloroethan -1-ol and NaHCO3

    (d)

    ethanol and H2O

  16. 2 Marks
    15 x 2 = 30
  17. Arrange the following in the decreasing order of order of acid strength.

  18. How will you distinguish between formaldehyde and acetaldehyde?

  19. Convert hex-4-ennitrileto hex-4-enal.

  20. How is the conversion of acetonitrile to acetic acid effected?

  21. What is glacial acetic acid? How is it obtained.

  22. Complete the following:
    (i) 
    (ii) 

  23. How will you distinguish between aniline and ethylamine.

  24. \({ C }_{ 2 }{ H }_{ 3 }N\xrightarrow [ Ether ]{ LiAl/{ H }_{ 4 } } B\underrightarrow { HN{ O }_{ 2 } } \) Identify A, Band C

  25. What is 'spirit of nitre'? Give its use.

  26. Define nucleotide.

  27. The two strands in DNA are not identical but are complementary explain.

  28. What is the main function of tRNA?

  29. How are disaccharides classified? Give example.

  30. Name the two constituent of starch.

  31. The sucrose that we eat in daily life is converted into glucose and fructose. Name the enzyme which facilitates this chemical reaction.

  32. 3 Marks
    15 x 3 = 45
  33. Give the basic requirement for vapour phase refining.

  34. Give one example for each of the following
    (i) icosogens
    (ii) tetragen
    (iii) prictogen
    (iv) chalcogen

  35. Complete the following reactions
    a.\(B(OH)+NH_{ 3 }+NH\longrightarrow \)
    b.\(Na_{ 2 }B_{ 2 }{ O }_{ 7 }+{ { H }_{ 2 }{ SO }_{ 4 }+{ H }_{ 2 }O\longrightarrow }\)
    c.\({ B }_{ 2 }{ H }_{ 6 }+2NaOH+2{ H }_{ 2 }O\longrightarrow \)
    d.\({ B }_{ 2 }{ H }_{ 6 }+{ CH }_{ 3 }OH\longrightarrow \)
    e.\({ BF }_{ 3 }+9{ H }_{ 2 }O\longrightarrow \)
    f.\(HCOOH+{ H }_{ 2 }{ SO }_{ 4 }\)
    g.\(SiCl_{ 4 }+{ C }_{ 2 }{ H }_{ 5 }OH\longrightarrow \)
    h.\(SiCl_{ 4 }+{ NH }_{ 3 }\longrightarrow \)
    i.\(B+NaOH\longrightarrow \)
    j.\({ H }_{ 2 }{ B }_{ 4 }{ O }_{ 7 }\overset { Red\quad hot }{ \rightarrow } \)

  36. Compare lanthanides and actinides

  37. Give the difference between double salts and coordination compounds.

  38. The rate of formation of a dimer in a second order reaction is 7.5 X 10-3mol L-1 s-1 monomer concentration. Calculate the rate constant.

  39. (i) A first order reaction takes 8 hours for 90% completion. Calculate the time required for 80% completion. (log 5 = 0.6989 ; log10 = 1)

  40. Calculate the pH of 1.5\(\times\)10-3Msolution of Ba(OH)2

  41. Derive an expression for the hydrolysis constant and degree of hydrolysis of salt of strong acid and weak base

  42. Arrange the following solutions in the decreasing order of specific conductance.
    i) 0.01M KCl
    ii) 0.005M KCl
    iii) 0.1M KCl
    iv) 0.25 M KCl
    v) 0.5 M KCl

  43. Peptising agent is added to convert precipitate into colloidal solution. Explain with an example.

  44. What is meta merism? Give the structure and IUPAC name of metamers of 2-methyoxy propane

  45. Arrange the following
    i. In increasing order of solubility in water, C6H5 NH2,(C2H5)2 NH,C2H5NH2
    ii. In increasing order of basic strength
    a) aniline, p- toludine and p – nitroaniline
    b) C6H5 NH2,C6H5 NHCH3,C6H5NH2 ,p-Cl-C6- H4-NH2
    iii. In decreasing order of basic strength in gas phase
    (C2H5)NH2 ,(C2H5)NH, (C2H5)5N and NH3
    iv. In increasing order of boiling point
    C6H5OH, (CH3)2NH, C2H5NH2
    v. In decreasing order of the pKb values
    C2H5NH2, C6H5NHCH3.(C2H5) NH and CH3NH2
    vi. Increasing order of basic strength
    C2H5NH2,C6H5NH(CH3)2 ,(C2H5)2 NH and CH3NH2
    vii. In decreasing order of basic strength

  46. How will you prepare propan – 1- amine from
    i) butane nitrile
    ii) propanamide
    ii) 1- nitropropane

  47. What are drugs? How are they classified

  48. 5 Marks
    15 x 5 = 75
  49. Give the structure for the following compounds.
    (i) pentaamminechlorocobalt (III) ion
    (ii) Triamminetrinitrito- k N cobalt (III)
    (ill) tetraammineaquabromidooobalt(III)nitrate
    (iv) Dichloridobisethane-1 )2-diamine) cobalt (lIl) chloride
    (v) Tetraamminecopper (lI)sulphate

  50. What are stoichiometric defects in ionic solids? Explain

  51. Rate constant of a first order reaction is 0.45 sec-1, calculate its half life.

  52. Calculate the pH of 0.1 M NH4OH if Kb = 1.75 x 10-5

  53. If E1 = 0.5 V corresponds to Cr3++ 3e- ➝ Cr(s) and E= 0.41V corresponds to Cr3++ e- ➝ Cr2+ reactions, calculate the emf (E3) of the reaction Cr2++ 2 e- ➝ Cr(s)

  54. Write the characteristics of catalysts.

  55. An organic compound A of molecular formula C3H6O on reduction with LiAlH4 gives B. Compound B gives blue colour in Victor Meyer's test and also forms a chloride C with SOCl2. The chloride on treatment with alcoholic KOH gives D. Identify A) B)C and D and explain the reactions

  56. Write all possible isomers with molecular formula C4H10O and name them.

  57. Illustrate the reducing property of acetaldehyde with examples

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

  59. Compound A with molecular formula C7H6O reduces Tollen's reagent and also gives Cannizaro reaction. A on oxidation gives the compound B with molecular formula C7H6O2 Calcium salt of B on dry distillation gives the compound C with molecular formula CI3H10O. Find A, Band C. Explain the reaction

  60. Account for the following:
    (i) Nitroethane is soluble NaOH
    (ii) Nitroethane reacts with nitrous acid
    (iii) 2-methyl-2-nitro propane has neither of the properties.

  61. Give the uses of carbohydrates.

  62. Explain Receptor as drug targets.

  63. Styrene polymerises to polystyrene when heated in the presence of peroxide initiator.
    (i) what is the mechanism involved?
    (ii) Give the initiation step for the above process.
    (iii) How does the chain propogate in the above mechanism?
    (iv) How is the above chain reaction terminated?

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