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Important Questions Part-X

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. Considering Ellingham diagram, which of the following metals can be used to reduce alumina? (NEET-2018)

    (a)

    Fe

    (b)

    Cu

    (c)

    Mg

    (d)

    Zn

  2. Which of the following is not true with respect to Ellingham diagram?

    (a)

    Free energy changes follow a straight line. Deviation occurs when there is a phase change.

    (b)

    The graph for the formation of CO2 is a straight line almost parallel to free energy axis.

    (c)

    Negative slope of CO shows that it becomes more stable with increase in temperature

    (d)

    Positive slope of metal oxides shows that their stabilities decrease with increase in temperature

  3. Name the process by which elements such as germanium, silicon and galium are refined.

    (a)

    Vapour phase method

    (b)

    Electrolytic refining

    (c)

    Zone refining

    (d)

    Van-Arkel method

  4. Identify the halide ore among the following

    (a)

    Epsom Salt

    (b)

    Pyrolusite

    (c)

    Anglesite

    (d)

    Rock Salt

  5. Ignition mixture used in aluminothermite process is

    (a)

    Cr + AI2O3

    (b)

    Mg + BaO2

    (c)

    AI + Cr2O3

    (d)

    Ba+MgO

  6. Boric acid is an acid because its molecule (NEET)

    (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.

  7. Oxidation state of carbon in its hydrides

    (a)

    +4

    (b)

    -4

    (c)

    +3

    (d)

    +2

  8. 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

  9. Aluminium is used for making alloys because of its _____

    (a)

    resistance to corrosion

    (b)

    poor conductivity

    (c)

    heaviness

    (d)

    all of these

  10. Group 14 elements have general electronic configuration _______

    (a)

    ns2

    (b)

    ns2np4

    (c)

    ns2np6

    (d)

    ns2np2

  11. P4O6 reacts with cold water to give

    (a)

    H3PO3

    (b)

    H4P2O7

    (c)

    HPO3

    (d)

    H3PO4

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

    (a)

    S4O62-

    (b)

    S2O62-

    (c)

    SO42-

    (d)

    SO32-

  13. Which is dibasic?

    (a)

    Orthophosphoric acid

    (b)

    Pyrophosphoric acid

    (c)

    Orthophosphorus acid

    (d)

    Hypophosphorus acid

  14. Oxalic acid on heating with cone H2SO4 gives

    (a)

    CO only

    (b)

    CO2 only

    (c)

    CO2+ H20

    (d)

    CO + CO2 + H2O

  15. Orthophosphorus acid on heating gives________

    (a)

    Hypophosphorus

    (b)

    Orthophosphoric acid

    (c)

    Phosphine gas

    (d)

    both (b) and (c)

  16. Among the transition metals of 3d series, the one that has highest negative \(\left( \frac { M^{ 2+ } }{ M } \right) \) standard electrode potential is

    (a)

    Ti

    (b)

    Cu

    (c)

    Mn

    (d)

    Zn

  17. Which of the following compounds is colourless?

    (a)

    Fe3+

    (b)

    Ti4+

    (c)

    Co2+

    (d)

    Ni2+

  18. Ce (Z=58) and Yb (Z=70) exhibits stable +4 and +2 oxidation states respectively. This is because

    (a)

    Ce4+ and Yb2+acquire f7 configuration

    (b)

    Ce4+ and Yb2+ acquire f0 configuration

    (c)

    Ce4+ and Yb2+acquire fand f14 configuration

    (d)

    Ce4+and Yb2+ acquire f0 and f14 configuration

  19. Which of the following ions will exhibit colour inaqueous solutions?

    (a)

    SC3+(Z=21)

    (b)

    Ti3+(Z =22)

    (c)

    La3+(Z=57)

    (d)

    Lu3+(Z=71)

  20. FeSO4 on heating gives ____________

    (a)

    SO2 and O2

    (b)

    SOand SO3

    (c)

    SO2

    (d)

    SO3

  21. A complex in which the oxidation number of the metal is zero is

    (a)

    K4[fe(CN)6]

    (b)

    [Fe(CN)3(NH3)5]

    (c)

    [Fe(CO)5]

    (d)

    both (b) and (c)

  22. Which of the following is paramagnetic in nature?

    (a)

    [Zn(NH3)4]2+

    (b)

    [Co(NH3)6]3+

    (c)

    [Ni(H2O)6]2+

    (d)

    [Ni(CN)4]2-

  23. Which of the following co-ordination compounds would exhibit optical isomerism?

    (a)

    Pemtaamminenitrocobalt (III) iodide

    (b)

    Diamminedichloropaltinum (II)

    (c)

    Tris-(ethylenediamine) cobalt (III) bromide

    (d)

    Transdicyanobis( ethylenediamine) chromium (III) chloride

  24. According to IUPAC, No is ______________

    (a)

    nitro

    (b)

    nitrosyl

    (c)

    nitrato

    (d)

    nitrito

  25. The structure of hexaaquatitanium (III) ion is __________

    (a)

    [Ti(H2O)6]3+

    (b)

    [Ti(H2O)6]3-

    (c)

    [Ti(H2O)5]H2O

    (d)

    [Ti(H2O)6]

  26. Assertion : monoclinic sulphur is an example of monoclinic crystal system
    Reason: for a monoclinic system, \(a\neq b\neq c\) and \(\alpha =\gamma ={ 90 }^{ 0 },\beta \neq { 90 }^{ 0 }\)

    (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.

  27.  if ‘a’ stands for the edge length of the cubic system ; sc , bcc, and fcc. Then the ratio of radii of spheres in these systems will be respectively

    (a)

    \(\left( \cfrac { 1 }{ 2 } a;\cfrac { \sqrt { 3 } }{ 2 } a;\cfrac { \sqrt { 2 } }{ 2 } a \right) \)

    (b)

    \(\left( \sqrt { 1a } :\sqrt { 3a } :\sqrt { 2a } \right) \)

    (c)

    \(\left( \cfrac { 1 }{ 2 } a:\cfrac { \sqrt { 3 } }{ 4 } a:\cfrac { 1 }{ 2\sqrt { 2 } } a \right) \)

    (d)

    \(\cfrac { 1 }{ 2 } a:\sqrt { 3 } a:\cfrac { 1 }{ \sqrt { 2 } } a\)

  28. The mass of unit cell of Na2O is _________

    (a)

    Twice the formula mass of Na2O

    (b)

    Four times the formula mass of Na2O

    (c)

    Six times the formula mass of Na2O

    (d)

    Thrice the formula mass of Na2O

  29. The number of cesium ion per unit cell in CsCI crystal system is________.

    (a)

    4

    (b)

    8

    (c)

    6

    (d)

    1

  30. Structure of B2O3 is _____

    (a)

    trigonal planar

    (b)

    tetrahedral

    (c)

    octahedral

    (d)

    cubic

  31. Consider the following statements :
    (i) increase in concentration of the reactant increases the rate of a zero order reaction.
    (ii) rate constant k is equal to collision frequency A if Ea = 0
    (iii) rate constant k is equal to collision frequency A if Ea =0
    (iv) a plot of ln (k) vs T is a straight line.
    (v) a plot of ln (k) vs \(\left( \cfrac { 1 }{ T } \right) \) is a straight line with a positive slope.
    Correct statements are

    (a)

    (ii) only

    (b)

    (ii) and (iv)

    (c)

    (ii) and (v)

    (d)

    (i), (ii) and (v)

  32. In a homogeneous reaction \(A\longrightarrow B+C+D\) the initial pressure was P0 and after time t it was P. expression for rate constant in terms of P0, P and t will be

    (a)

    \(k=\left( \cfrac { 2.303 }{ t } \right) log\left( \cfrac { 2{ P }_{ 0 } }{ { 3P }_{ 0 }-P } \right) \)

    (b)

    \(k=\left( \cfrac { 2.303 }{ t } \right) log\left( \cfrac { { 2P }_{ 0 } }{ { P }_{ 0 }-P } \right) \)

    (c)

    \(k=\left( \cfrac { 2.303 }{ t } \right) log\left( \cfrac { 3{ P }_{ 0 }-P }{ 2P_{ 0 } } \right) \)

    (d)

    \(k=\left( \cfrac { 2.303 }{ t } \right) log\left( \cfrac { 2{ P }_{ 0 } }{ { 3P }_{ 0 }-2P } \right) \)

  33. How much time will be taken for 20 gm to reduce 5 g? [R = 2 x 10-3s-1 (I order reaction)]

    (a)

    693.1 s

    (b)

    693.1 s-1

    (c)

    6.931 s

    (d)

    6.931 s-1

  34. During a chemical reaction, the concentration of reaction

    (a)

    increases

    (b)

    decreases

    (c)

    remains constant

    (d)

    first increases and then decreases

  35. Activation energy is equal to _____________

    (a)

    Threshold energy + Energy of colloding molecules

    (b)

    Threshold energy

    (c)

    Threshold energy x Energy of colloiding molecules

    (d)

    Threshold energy - Energy of colloiding molecules

  36. pH of a saturated solution of Ca(OH)2 is 9. The Solubility product ( Ksp) of Ca(OH)2

    (a)

    0.5 ×10-15

    (b)

    0.25 ×10-10

    (c)

    0.125 ×10-15

    (d)

    0.5 ×10-10

  37. 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

  38. An aqueous solution with pH value zero is

    (a)

    acidic

    (b)

    basic

    (c)

    amphoteric

    (d)

    neutral

  39. A drop of hydrochloric acid is added to pure water, its pH _____

    (a)

    increases

    (b)

    decreases

    (c)

    increases and then decreases

    (d)

    resist the change in pH and so remains unaltered

  40. The ionic product of water at 25°C is __________

    (a)

    1 x 10-7

    (b)

    1 X 107

    (c)

    1 X 10-14

    (d)

    1 X 1014

  41. The molar conductivity of a 0.5 mol dm-3 solution of AgNO3 with electrolytic conductivity of 5.76 ×10−3 S cm−1at 298 K is

    (a)

    2.88 S cm2mol-1

    (b)

    11.52 S cm2mol-1

    (c)

    0.086 S cm2mol-1

    (d)

    28.8 S cm2 mol -1

  42. How many faradays of electricity are required for the following reaction to occur
    MnO→ Mn 4-

    (a)

    5F

    (b)

    3F

    (c)

    1F

    (d)

    7F

  43. Faraday's laws of electrolysis are related to

    (a)

    atomic number of the cation

    (b)

    atomic number of the anion

    (c)

    equivalent weight of the electrolyte

    (d)

    speed ofthe cation

  44. The specific conductance of a 0.01 M solution of KCI is 0.0014 ohm-1 em-1 at 25°C. Its equivalent conductance is

    (a)

    14 ohm-1 cm2eq-1

    (b)

    140 ohm-1 cm2eq-1

    (c)

    1.4 ohm-1 cm2eq-1

    (d)

    0.14 ohm-1 cm2eq-1

  45. When two half cells of Daniel cell is connected, a spontaneous ______________ reaction takes place resulting in the flow of electrons from anode to cathode

    (a)

    reduction

    (b)

    oxidation

    (c)

    redox

    (d)

    hydration

  46. 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

  47. Match the following

    a Pure nitrogen i Chlorine
    b Haber process ii Sulphuric acid
    c Contact process iii Ammonia
    d Deacons Process iv sodium azide (or) Barium azide

    Which of the following is the correct option?

    (a)
    A B C D
    i ii iii iv
    (b)
    A B C D
    ii iv i iii
    (c)
    A B C D
    iii iv ii i
    (d)
    A B C D
    iv iii ii i
  48. In case of physical adsorption, there is desorption when

    (a)

    temperature increases

    (b)

    temperature decreases

    (c)

    pressure increases

    (d)

    concentration increases

  49. The combination of the two layers of charges around the sol particle is called

    (a)

    Brownian movement

    (b)

    Tyndall effect

    (c)

    Helmholtz double layer

    (d)

    None of these

  50. The platinum catalyst used in the oxidation of SO2 by contact process is poisoned by

    (a)

    As2O3

    (b)

    V2O5

    (c)

    Fe2O3

    (d)

    CuCl2

  51. Assertion : Phenol is more reactive than benzene towards electrophilic substitution reaction
    Reason : In the case of phenol, the intermediate arenium ion is more stabilized by resonance

    (a)

    if both assertion and reason are true and reason is the correct explanation of assertion.

    (b)

    if 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.

  52. Which of the following compound can be used as artireeze in automobile rediators?

    (a)

    methanol

    (b)

    ethanol

    (c)

    Neopentyl alcohol

    (d)

    ethan -1, 2-diol

  53. Predict the structure of propane-1,2 diol

    (a)

    CH2 (OH) - CH2CH2OH

    (b)

    HOCH2 - CH2OH

    (c)

    CH3CH (OH) CH2OH

    (d)

    None of these

  54. The number of secondary alcoholic group in glycerol is ________

    (a)

    1

    (b)

    2

    (c)

    3

    (d)

    0

  55. Among the following compounds strongest acid is _________

    (a)

    HC≡CH

    (b)

    C6H6

    (c)

    C2H6

    (d)

    CH3OH

  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. Reduction of ketone gives _______.

    (a)

    Primary alcohol

    (b)

    Secondary alcohol

    (c)

    Primary amide

    (d)

    Secondary amide

  59. The test to distinguish HCOOH and CH3COOH is/are ________.

    (a)

    Tollens reagent test

    (b)

    Litmus test

    (c)

    Sodium bicarbonate test

    (d)

    Both (b) and (c)

  60. The decarboxylating agent is ___________.

    (a)

    soda lime

    (b)

    lime water

    (c)

    quick lime

    (d)

    lime of milk

  61. Part - B

    40 x 2 = 80
  62. What is the difference between minerals and ores?

  63. Describe a method for refining nickel

  64. Name the two steps involved in the extraction of crude metal

  65. Why is the froth floatation method selected for the concentration of sulphide ores?

  66. Write a short note on anamolous properties of the first element of p-block

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

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

  69. Which one is more soluble in diethyl ether, anhydrous Alcl3 or hydrated Alcl3? Explain in terms of bonding.

  70. What is inert pair effect?

  71. Explain why fluorine always exhibit an oxidation state of -1?

  72. There is a huge difference between the melting and boiling points of oxygen and sulphur. Why?

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

  74. What are transition metals? Give four examples.

  75. Explain the oxidation states of 3d series elements.

  76. Arrange the following in increasing order of acidic character?
    CrO3, CrO, Cr2O3

  77. A poster suggests the following life style on the part of families / individuals.
    (i) Which environmental values are promoted through these life style?
    (ii) Suggest one additional life style action for promotion of green chemistry.
    (iii) Give reason for the bleaching action of  KMnO4

  78. Write the IUPAC names for the following complexes
    i) Na2[Ni(EDTA)]
    II) [Ag(CN)2)
    iii) [Co9en)3]2(SO4)3
    iv)[Co(ONO)(NH3)5]2+
    v)[Pt(NH3)2Cl(NO2)]

  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. What are stereoisomers?

  81. Draw the Cis and trans isomer of MA2B2 type

  82. Why do solids have a definite volume?

  83. What is point defect in crystals?

  84. Explain the rate determining step with an example.

  85. 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.

  86. Rate of chemical reaction is not uniform throughout. Justify you answer:

  87. The reaction A + 2B ⟶ C obeys the rate equation. Rate = \(K{ \left[ A \right] }^{ \frac { 1 }{ 2 } }{ \left[ B \right] }^{ \frac { 3 }{ 2 } }\) What is the order of the reaction?

  88. What are lewis acids and bases? Give two example for each.

  89. Calculate the pH of 0.04 M HNO3 Solution.

  90. What are the two types of buffer? Give an example for each.

  91. Magnesium is not precipitated from a solution of its salt by a mixture of NH4OH and NH4Cl. Explain

  92. Describe the electrolysis of molten NaCl using inert electrodes

  93. State Faraday’s Laws of electrolysis

  94. Explain the function of a salt bridge in an electrochemical cell.

  95. Write the oxidation, reduction and overall redox reaction taking place in the Lithium ion battery.

  96. What are promoters? Give an example.

  97. Adsorption of a gas on the surface of solid is generally accompanied by decrease in entropy. Still it is a spontaneous process. Explain.

  98. What happens when ethylene reacts with alkaline KMnO4 solution?

  99. Which of the following does not give iodoform reaction?

  100. Write short note .on Kolbe's electrolytic reaction.

  101. Give any three uses of benzoic acid.

  102. Part - C

    22 x 3 = 66
  103. (A) Predict the conditions under which
    (i) Aluminium might be expected to reduce magnesia.
    (ii) Magnesium could reduce alumina.
    (B) Carbon monoxide is more effective reducing agent than carbon below 983K but, above this temperature, the reverse is true –Explain.
    (c) it is possible to reduce Fe2O3 by coke at a temperature around 1200K

  104. How oxides of metals are reduced by hydrogen?

  105. AlCl3 behaves like a lewis acid. Substantiate this statement.

  106. What happens to boranes at high temperatures?

  107. Give a reason to support that sulphuric acid is a dehydrating agent.

  108. Explain the commercial method of preparation of nitric acid. (or) How nitric acid is prepared by Ostwald's process

  109. What are interstitial compounds?

  110. Write chemical equations for the reactions involved in the manufacture of potassium permanganate from pyrolusite ore.

  111. Classify the following ligand based on the number of donor atoms
    a)NH3
    b)en
    c)ox2-
    d) triaminotriethylamine
    e) pyridine

  112. Aqueous copper sulphate solution (blue) gives
    (i) a green precipitate with aqueous potassium fluoride.
    (ii) a bright green solution with aqueous potassium chloride. Explain these experimental results.

  113. State Bragg's law.

  114. A gas phase reaction has energy of activation 200 kJ mol-1. If the frequency factor of the reaction is is 1.6 X1013s-1 Calculate the rate constant at 600 K.(e-40.09=3.8X10-48)

  115. What is the effect of temperature on the rate constant of a reaction? How can this temperature effect on rate constant be represented quantitatively?

  116. Define pH.

  117. What do you mean by buffer action?

  118. The conductivity of a 0.01M solution of a 1 :1 weak electrolyte at 298K is 1.5\(\times\)10-4 S cm−1.
    i) molar conductivity ozf the solution
    ii) degree of dissociation and the dissociation constant of the weak electrolyte
    Given that
    \(\lambda^{0}_{catlon}=248.2\quad S\) cm2 mol-1
    \(\lambda^{0}_{anlon}=51.8\quad S\) cm2 mol-1

  119. Write the cell representation of the galvanic cell in which the following reaction take place
    \({ Zn }_{ (s) }+Cu{ SO }_{ 4 }\rightarrow { ZnSO }_{ 4 }+{ Cu }_{ (s) }\)
    For the above cell. Identify the anode and cathode half cell.

  120. What are enzymes? Write a brief note on the mechanism of enzyme catalysis.

  121. Name various techniques by which a colloid can be deemulsified.

  122. Write the mechanism of acid catalysed dehydration of ethanol to give ethane.

  123. How do primary, secondary and tertiary alcohols differ in terms of their oxidation?

  124. What is acidity constant? How is it expressed.

  125. Part - D

    12 x 5 = 60
  126. List the applications of iron

  127. How are silicates classified? Give an example for each type of silicate.

  128. Explain the oxidising property of sulphuric acid.

  129. Justify the following statement.
    "Elements of the first transition series possess many properties different from those of heavier transition elements".

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

  131. An element with molar mass 2.7 x 10-2 kg mol forms a cubic unit cell with edge length 405 pm. If its density is 2.7 x 103 kg m-3, What is the nature of the cubic unit cell?

  132. A first order reaction completes 25% of the reaction in 100 mins. What are the rate constant and half life values of the reaction?

  133. Calculate the pH of 0.02 MHCl.

  134. The emf values of the cell reactions Fe3++ e- ⇾ Fe2+ and Ce2+ ⇾ Ce3+ e- are 0.61 V and -0.85 V respectively. Construct the cell such that the free energy of the cell is negative. Calculate the emf of the cell.

  135. Write any five applications of colloids in day - to day life.

  136. What is major product formed when 3,3-dimethyl-2-butanol is heated in the presence of H2SO4.

  137. An organic compound (A) C2H3OCI on treatment with Pd and BaSO4 gives (B) C2H4O which answers iodoform test. (B) when treated with cone. H2SO4 undergoes polymerisation to give (C) .a cyclic compound. Identify (A), (B) and (C) and explain the reactions.

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