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Important Questions Part-II

12th Standard EM

    Reg.No. :
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Chemistry

Time : 01:00:00 Hrs
Total Marks : 60

    Part - A

    60 x 1 = 60
  1. The incorrect statement among the following is

    (a)

    Nickel is refined by Mond’s process

    (b)

    Titanium is refined by Van Arkel’s process

    (c)

    Zinc blende is concentrated by froth floatation

    (d)

    In the metallurgy of gold, the metal is leached with dilute sodium chloride solution

  2. Which of the following plot gives Ellingham diagram

    (a)

    \(\Delta SVsT\)

    (b)

    \(\Delta { G }^{ 0 }VsT\)

    (c)

    \(\Delta { G }^{ 0 }Vs\cfrac { 1 }{ T } \)

    (d)

    \(\Delta { G }^{ 0 }Vs{ T }^{ 2 }\)

  3. In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with

    (a)

    Iron sulphide (FeS)

    (b)

    Carbon monoxide (CO)

    (c)

    Copper (I) sulphide (Cu2S)

    (d)

    Sulphur dioxide (S02)

  4. Concentration of copper glance is done by

    (a)

    leaching

    (b)

    magnetic separation

    (c)

    froth flotation

    (d)

    hydraulic washing

  5. Froth floatation process is suitable for concentrating ______ores.

    (a)

    oxide

    (b)

    carbonate

    (c)

    sulphide

    (d)

    halide

  6. Carbon atoms in fullerene with formula C60 have

    (a)

    sp3 hybridised

    (b)

    sp hybridised

    (c)

    sp2 hybridised

    (d)

    partially sp2 and partially sp3 hybridised

  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. Select the incorrect statement regarding B2H6.

    (a)

    It contains B-B ionic bond

    (b)

    Each boron is Sp3 hybridised

    (c)

    It has two types of hydrogen bonds

    (d)

    it is used as a reducing agent

  9. Graphite has

    (a)

    2-d sheet structure

    (b)

    Vander waals force between successive layers of carbon sheets

    (c)

    Sp2 hybridised carbon linked with other three carbon atoms in hexagonal planar structure

    (d)

    all the above

  10. Silicones are ______

    (a)

    ortho silicates

    (b)

    water repellent thermal insulators

    (c)

    both (a) and (b)

    (d)

    None of these

  11. The basicity of pyrophosphorous acid ( H4P2O5) is

    (a)

    4

    (b)

    2

    (c)

    3

    (d)

    5

  12. When copper is heated with conc HNO3 it produces

    (a)

    Cu(NO3)2 , NO and NO2

    (b)

    Cu(NO3)2 and N2O

    (c)

    Cu(NO3)2 and NO2

    (d)

    Cu(NO3)2 and NO

  13. Catenation property of group 15 elements, follow the order

    (a)

    N < P < As < Sb < Bi

    (b)

    P >> N > As > Sb > Bi

    (c)

    P < N < As < Sb < Bi

    (d)

    N>> P > As > Sb > Bi

  14. Pick the wrong one among the following

    (a)

    F2 - Yellow

    (b)

    Br2 - Red

    (c)

    Cl2 - Colourless

    (d)

    I2- Violet

  15. Oxalic acid on heating with cone H2SO4 gives

    (a)

    CO only

    (b)

    CO2 only

    (c)

    CO2+ H20

    (d)

    CO + CO2 + H2O

  16. Which of the following statements is not true?

    (a)

    on passing H2S, through acidified K2Cr2O7 solution, a milky colour is observed

    (b)

    Na2Cr2O7 is preferred over K2Cr2O7 in volumetric analysis

    (c)

    K2Cr2O7 solution in acidic medium is orange in colour

    (d)

    K2Cr2O7 solution becomes yellow on increasing the PH beyond 7

  17. A white crystalline salt (A) react with dilute HCl to liberate a suffocating gas (B) and also forms a yellow precipitate . The gas (B) turns potassium dichromate acidified with dil H2SO4 to a green coloured solution(C).  A, B and C are respectively

    (a)

    Na2SO3, SO2, Cr2(SO4)3

    (b)

    Na2S2O3, SO2, Cr2(SO4)3

    (c)

    Na2S, SO2,Cr2(SO4)3

    (d)

    Na2SO4, SO2, Cr2(SO4)3

  18. On oxidation with KMnO4 in acidic medium, SO2 is oxidised to ___________

    (a)

    SO2

    (b)

    H2SO4

    (c)

    SO32-

    (d)

    H2S

  19. Acidified solution of chromic acid on treatment with H2O2 give blue colour which is due to ____________

    (a)

    CrO3 + H2O + O2

    (b)

    H2Cr2O7+ H2O + CO2

    (c)

    Cr2O3 + H2O + O2

    (d)

    CrO5 + H2O

  20. _________ is known as Bayer's reagent.

    (a)

    Hot dilute alkaline KMnO4

    (b)

    Cold dilute alkaline KMnO4

    (c)

    Hot Conc. acidic KMnO4

    (d)

    Cold Conc. acidic KMnO4

  21. Which type of isomerism is exhibited by [Pt(NH3)2Cl2]?

    (a)

    Coordination isomerism

    (b)

    Linkage isomerism

    (c)

    Optical isomerism

    (d)

    Geometrical isomerism

  22. 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+

  23. The coordination polyhedron of the complex [Cr(H2O)6]CI3 is____________

    (a)

    square planar

    (b)

    tetrahedral

    (c)

    trigonal

    (d)

    octahedral

  24. ____________is used as an antitumor drug in cancer treatment.

    (a)

    Ca - EDTA

    (b)

    Cis - platin

    (c)

    Sodium thio sulphate

    (d)

    Nickel chloride

  25. Phthalo blue - a bright blue figment is a complex of ________________

    (a)

    Copper (I) ion

    (b)

    Copper (II) ion

    (c)

    Nickel (II) ion

    (d)

    Nickel (IV) ion

  26. The radius of an atom is 300pm, if it crystallizes in a face centered cubic lattice, the length oif the edge of the unit cell is

    (a)

    488.5pm

    (b)

    848.5pm

    (c)

    884.5pm

    (d)

    484.5pm

  27. Assertion: due to Frenkel defect, density of the crystalline solid decreases.
    Reason: in Frenkel defect cation and anion leaves the crystal

    (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

  28. Which of the following features is false regarding the structure of CsCI?

    (a)

    It has bee arrangements

    (b)

    Co-ordination number for each ion is 8

    (c)

    Number of atoms in a unit cell is 4

    (d)

    The radius ratio (r+/r-) is 0.93

  29. Which among the following is an amorphous solid?

    (a)

    Graphite

    (b)

    SiO2

    (c)

    Sic

    (d)

    Diamond

  30. The coordination number of ZnS is _________.

    (a)

    3

    (b)

    4

    (c)

    6

    (d)

    8

  31. After 2 hours, a radioactive substance becomes \(\left( \cfrac { 1 }{ 16 } \right) ^{ th }\) of original amount Then the half life ( in min) is

    (a)

    60 minutes

    (b)

    120 minutes

    (c)

    30 minutes

    (d)

    15 minutes

  32. This reaction follows first order kinetics. The rate constant at particular temperature is 2.303X10-2 hour-1 The initial concentration of cyclopropane is 0.25 M. What will be the concentration of cyclopropane after 1806 minutes? (log 2 = 0.3010)

    (a)

    0.125 M

    (b)

    0.215 M

    (c)

    0.25 X 2.303 M

    (d)

    0.05 M

  33. (a)

    It is a 2 steps reaction, step 1 is slower than step 2

    (b)

    It is a 2 steps reaction, step 2 is slower than step 1.

    (c)

    Single step reaction where B is a activated complex

    (d)

    Single step reaction in which B is a reaction intermediate.

  34. The graph between. the log K verrus \(\frac { 1 }{ T } \) is a straight line. The slope of the line is

    (a)

    \(\frac { -2.303R }{ Ea } \)

    (b)

    \(\frac { Ea }{ 2.303R } \)

    (c)

    \(\frac { 2.303R }{ Ea } \)

    (d)

    \(\frac { Ea }{ 2.303R } \)

  35. For a general reaction aA + bB ⟶Products, the rate of the reaction is equal to_____________.

    (a)

    k[A]p [B]q

    (b)

    k [A] [B]

    (c)

    k

    (d)

    \(\frac { 1 }{ k } \)

  36. Which of these is not likely to act as lewis base?

    (a)

    BF3

    (b)

    PF3

    (c)

    CO

    (d)

    F

  37. The pH of an aqueous solution is Zero. The solution is

    (a)

    slightly acidic

    (b)

    strongly acidic

    (c)

    neutral

    (d)

    basic

  38. HClis a strong acid since

    (a)

    It can be easily oxidised

    (b)

    It canbe easilyionised

    (c)

    It dissociates completely to give H+ ions in solution

    (d)

    It can be easily oxidised and It can be easilyionised

  39. The pH of a solution containing 0.1 N NaOH solution is

    (a)

    1

    (b)

    10-1

    (c)

    13

    (d)

    10-13

  40. According to Lowry - Bronsted theory, an acid is a ______

    (a)

    electron donor

    (b)

    electron acceptor

    (c)

    proton donor

    (d)

    prof on acceptor

  41. Among the following cells
    I) Leclanche cell
    II) Nickel – Cadmium cell
    III) Lead storage battery
    IV) Mercury cell
    Primary cells are

    (a)

    I and IV

    (b)

    I and III

    (c)

    III and IV

    (d)

    II and III

  42. In the electrochemical cell: Zn|ZnSO4 (0.01M)|| CuSO4 (1.0M)| Cu, the emf of this Daniel cell is E1. When the concentration of ZnSO4 is changed to 1.0M and that CuSO4 changed to 0.01M, the emf changes to E2. From the followings, which one is the relationship between E1 and E2?

    (a)

    E1 < E2

    (b)

    E1 > E2

    (c)

    E2=0 \(\uparrow\)E1

    (d)

    E1=E2

  43. The equivalent conductivity of CH3COOH at 25°C is 80 ohm-1 cm2 eq-1 and at infmite dilution 400 ohm-1 cm-1 eq-1. The degree of dissociation of CH3COOH is

    (a)

    1

    (b)

    0.2

    (c)

    0.1

    (d)

    0.3

  44. 1 mho is equal to

    (a)

    1 siemen

    (b)

    1 second

    (c)

    1 ohm

    (d)

    none of the above

  45. Low molar conductivity at high concentration is due to _____________

    (a)

    High attractive force between oppositively charged ions

    (b)

    Viscous drag due to greater solvation

    (c)

    Both High attractive force between oppositively charged ions and Viscous drag due to greater solvation

    (d)

    Neither High attractive force between oppositively charged ions and Viscous drag due to greater solvation

  46. Which one of the following characteristics are associated with adsorption?

    (a)

    \(\Delta\)G and \(\Delta\)H are negative but \(\Delta\)S is positive

    (b)

    \(\Delta\)G and \(\Delta\)S are negative but \(\Delta\)H is positive

    (c)

    \(\Delta\)G is negative but \(\Delta\)H and \(\Delta\)S are positive

    (d)

    \(\Delta\)G,\(\Delta\)H and \(\Delta\)S all are negative.

  47. 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

  48. _______is a measure of protecting power ofa colloid.

    (a)

    Colloid number

    (b)

    Coagulation number

    (c)

    Goldnumber

    (d)

    Sol number

  49. Butter and cream are examples of________type of emulsion.

    (a)

    O/O

    (b)

    O/W

    (c)

    W/W

    (d)

    W/O

  50. The process of hardening ofleather is called

    (a)

    coagulation

    (b)

    tanning

    (c)

    centrifuging

    (d)

    stabilization

  51. Which one of the following is the strongest acid

    (a)

    2 - nitrophenol

    (b)

    4 – chlorophenol

    (c)

    4– nitrophenol

    (d)

    3 – nitrophenol

  52. Williamson synthesis of preparing dimethyl ether is a / an /

    (a)

    SN1 reactions

    (b)

    SN2 reaction

    (c)

    electrophilic addition

    (d)

    electrophilic substitution

  53. The compound that acts as a solvent for Grignard reagent is :

    (a)

    Ethyl alcohol

    (b)

    Diethyl ether

    (c)

    Acetone

    (d)

    Benzene

  54. Ethers are insoluble in water due to the

    (a)

    absence of co-ordinate bond

    (b)

    presence of co-ordinate bond

    (c)

    absence of H - bond

    (d)

    presence of H - bond

  55. The ether used in perfumery is ________

    (a)

    diethyl ether

    (b)

    dimethyl ether

    (c)

    methyl phenyl ether

    (d)

    diphenyl ether

  56. 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

  57. The reagent used to distinguish between acetaldehyde and benzaldehyde is

    (a)

    Tollens reagent

    (b)

    Fehling’s solution

    (c)

    2,4 – dinitrophenyl hydrazine

    (d)

    semicarbazide

  58. Which . of the following compound is optically active?

    (a)

    CH3CH2COOH

    (b)

    HOOC-CH2-COOH

    (c)

    CH3CH(OH)COOH

    (d)

    Cl2CHCOOH

  59. Carboxylic acids are synthesised from Grignard reagent by the action of ________.

    (a)

    CO2

    (b)

    H2O

    (c)

    C6H5OH

    (d)

    CH3OH

  60. On fusion with KOH benzophenone undergoes __________, and gives potassium benzoate and ________.

    (a)

    disproportionation reaction, toluene

    (b)

    condensation reaction, toluene

    (c)

    disproportionation reaction, benzene

    (d)

    condensation reaction, benzene

  61. Part - B

    40 x 2 = 80
  62. What are the various steps involved in extraction of pure metals from their ores?

  63. Describe a method for refining nickel

  64. Name the ore that can be concentrated by magnetic separation method.

  65. What is the role of graphite rods in the electro metallurgy of aluminium?

  66. Describe briefly allotropism in p- block elements with specific reference to carbon

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

  68. What are the uses of boron trifluoride?

  69. What is phosgene? How is it prepared?

  70. Give the oxidation state of halogen in the following.
    a) OF2
    b) O2F2
    c) Cl2O3
    d) I2O4

  71. What are interhalogen compounds? Give examples.

  72. (i) Give correct order of boiling point of hydride of group 17.
    (ii) Fluorine exhibits only -1 oxidation state whereas other halogens show +1, +3, +5 and +7 oxidation state also Explain.

  73. Give reason for the following:
    F2 is more reactive than CIF3 but CIF3 is more reactive than Cl2

  74. What are inner transition elements?

  75. Explain why compounds of Cu2+ are coloured but those of Zn2+ are colourless.

  76. Write ionic equation for the reaction between Cr2O7-2 iODS and Fe2+ ions in acidic medium.

  77. Comparing La(OH)3 and Lu(OH)3, which is more basic and explain why?

  78. Write the formula for the following coordination compounds.
    a) potassiumhexacyanidoferrate(II)
    b) petacarbonyliron(0)
    c) pentaamminenitrito −k−N-cobalt(III)ion
    d) hexaamminecobalt(III)sulphate
    e) sodiumtetrafluoridodihydroxidochromate(III)

  79. Calculate the ratio of \(\cfrac { \left[ { Ag }^{ + } \right] }{ \left[ Ag\left( NH_{ 3 } \right) _{ 2 } \right] ^{ + } } \) in 0.2 M solution of NH3. If the stability constant for the complex \([Ag(NH_{ 3 })_{ 2 }]^{ \rightarrow }\)

  80. Arrange the following complex ions in the increasing order of crystal filed splitting energy (\({ \triangle }_{ 0 }\)) [CrCI6]3-, [Cr(CN)6]3-, [Cr(NH3)6]3+

  81. What are enantiomers?

  82. Distinguish between.
    Face - centred and body - centred unit cells.

  83. In CaF2 crystal, Ca2+ ions are present in arrangement. Calculate the number of F- ions in the unit cell.

  84. The rate law for a reaction of A, B and C has been found to be rate =k[A]2[B][L]3/2 How would the rate of reaction change when
    (i) Concentration of [L] is quadrupled
    (ii) Concentration of both [A] and [B] are doubled
    (iii) Concentration of [A] is halved
    (iv) Concentration of [A] is reduced to \(\left( 1/3 \right) \) and concentration of [L] is quadrupled.

  85. For a reaction A + B ⟶ C, the rate of the reaction is denoted \(\frac { -dA }{ dt } \) or \(\frac { -dB }{ dt } \) or \(\frac { +dC }{ dt } \). State the significance of plus and minus sign.

  86. How does the value of rate constant vary with reactant constant.

  87. Consider the oxidation of nitric oxide to form NO2
    2NO(g) + O2(g) ➝2NO (g)
    (a). Express the rate of the reaction in terms of changes in the concentration of NO,O2 and NO2.
    (b). At a particular instant, when [O2] is decreasing at 0.2 mol L−1s−1 at what rate is [NO2] increasing at that instant?

  88. Discuss the Lowery – Bronsted concept of acids and bases.

  89. Calculate the pH of 0.04 M HNO3 Solution.

  90. When temperature is increased, will ionic product of water increase or decrease? Give reason to justify your answer.

  91. Write down the conjugate acid and base of the following
    (i) NH3
    (ii) HSO-4

  92. Describe the electrolysis of molten NaCl using inert electrodes

  93. The resistance of a conductivity cell is measured as 190 Ω using 0.1M KCl solution (specific conductance of 0.1M KCl is 1.3 Sm-1) . When the same cell is filled with 0.003M sodium chloride solution, the measured resistance is 6.3KΩ. Both these measurements are made at a particular temperature. Calculate the specific and molar conductance of NaCl solution. Given that

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

  95. Give the expression that relates molar conductivity and degree of dissociation.

  96. What is Ultrafilteration?

  97. Explain the kinetic property of colloids.

  98. Name the only primary alcohol which gives positive iodoform test.

  99. State Saytzeff's rule.

  100. What is DIBAL -H? What is it used for?

  101. What happens when soda lime is treated with
    (i) CH3COONa
    (ii) C6H5COOH?

  102. Part - C

    22 x 3 = 66
  103. Give the basic requirement for vapour phase refining.

  104. Write the chemical composition of the following alloys and give anyone of its application.
    (i) Bronze
    (ii) Brass
    (iii) Stainless steelass

  105. 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.\({ H }_{ 2 }{ B }_{ 4 }{ O }_{ 7 }\overset { Red\quad hot }{ \rightarrow } \)

  106. What are the uses of diborane?

  107. How will you prepare chlorine in the laboratory?

  108. Out of H2O and H2S which one has higher bond angle and why?

  109. Compare lanthanides and actinides

  110. Explain the oxidising property of KMnO4 in natural medium. Give the equations.

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

  112. Mohr's salt answers the presence of Fe2+, NH4+and SO42- ions, whereas the potassium ferrithiocyanate will not answer Fe3+ and SCN ions give reason.

  113. What is the formula of a compound in which the element Y forms ccp lattice and atoms of X occupy 2/3rd of tetrahedral voids?

  114. Hydrolysis of methyl acetate in aqueous solution has been studied by titrating the liberated acetic acid against sodium hydroxide. The concentration of an ester at different temperatures is given below.

    t(min) 0 20 40 60
    v (ml) 20.2 25.6 29.5 32.8 50.4

    Show that the reaction is the first order reactions.

  115. Prove that the time required for the completion \({ \frac { 3 }{ 4 } }^{ th }\) of the reaction of a first
    order is twice the time required for the completion of a half of the reaction.

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

  117. For an aqueous solution of NH4CI, prove that [H+ ] = \(\sqrt { { K }_{ n }.C } \)

  118. Why is AC current used instead of DC in measuring the electrolytic conductance?

  119. Leclanche cell is a non-rechargeable cell. Answer the questions below with respect to Leclanche cell.
    (i) Anode
    (ii) Cathode
    (iii) Electrolyte
    (iv) Oxidation half cell reaction
    (v) Reduction half cell reaction.

  120. What do you mean by activity and selectivity of catalyst?

  121. Give three examples of enzyme catalyzed reactions.

  122. How is glycerol obtained commercially? State its uses.

  123. When tertiary butyl alcohol and 1-butanol are separately treated with a few drops of KMnO4, in one case only the purple colour disappears and a brown precipitate is formed. Which of the two alcohols gives the above reaction and what is that brown precipitate?

  124. Organic compound with molecular formula C3H6O has two isomers (A) and (B). (A) on heating with NaOH in I2 forms a yellow precipitate while (B) does not. Identify the isomers A and B and explain the reactions.

  125. Part - D

    12 x 5 = 60
  126. Explain refming of titanium by Van-Arkel method.

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

  128. Howdoes sulphuric acid react with metals at various conditions

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

  130. What are the postulates of valance bond theory? Give its limitations.

  131. What are the general characteristics of solids?

  132. The decomposition of NH3 on platinum surface is zero reaction. What are the rate of production of N2 and H2 it K = 2.5 X 10-4mol L-1 S-1?

  133. If a solution has a pH of 7.41, determine its H+ concentration.

  134. The standard reduction potential for the reaction Sn4+ + 2e- ⟶ Sn2+ is + 0.15v. Calcuate the free energy change of the reaction.

  135. Give the special characteristics of enzyme catalysed reactions.

  136. 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

  137. An organic compound A (C7H6OL) reduces Tollen's reagent. On treating with an alkali compound A forms Band C. B on treating with sodalime forms benzene and C (C7HsO) is an antiseptic. Identify compounds A, B and C. Explain the reactions

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