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#### Important Questions Part-VII

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. Which of the metal is extracted by Hall-Heroult process?

(a)

Al

(b)

Ni

(c)

Cu

(d)

Zn

2. Zinc is obtained from ZnO by

(a)

Carbon reduction

(b)

Reduction using silver

(c)

Electrochemical process

(d)

Acid leaching

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

(a)

1

(b)

0

(c)

+2

(d)

-2

4. Steelis an alloy of___________

(a)

iron and carbon

(b)

iron and calcium

(c)

copper and carbon

(d)

copper and iron

5. Galena is_________

(a)

PbS

(b)

ZnS

(c)

Ag2S

(d)

FeS2

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 compound that is used in nuclear reactors as protective shields and control rods is

(a)

Metal borides

(b)

metal oxides

(c)

Metal carbonates d) metal carbide

(d)

none of these

8. Which one of the following compounds has similar structure to that of graphite?

(a)

Boron nitride

(b)

Boron Carbide

(c)

Aluminium Carbide

(d)

Aluminium Oxide

9. Chemical formula of phosgene is

(a)

COCl2

(b)

CaOCl2

(c)

CaCO3

(d)

COCI

10. All elements except carbon have the tendency to show maximum covalency of six ______

(a)

due to presence of vacant d-orbitals

(b)

due to absence of vacant d-orbitals

(c)

due to presence of partially filled d-orbitals

(d)

due to presence of completely filled d-orbitals

11. The molarity of given orthophosphoric acid solution is 2M. its normality is

(a)

6N

(b)

4N

(c)

2N

(d)

none of these

12. Assertion : bond dissociation energy of fluorine is greater than chlorine gas
Reason: chlorine has more electronic repulsion than fluorine.

(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

13. Which is dibasic?

(a)

Orthophosphoric acid

(b)

Pyrophosphoric acid

(c)

Orthophosphorus acid

(d)

Hypophosphorus acid

14. Pick the wrong one among the following

(a)

F2 - Yellow

(b)

Br2 - Red

(c)

Cl2 - Colourless

(d)

I2- Violet

15. The incorrect statement among the following is_________

(a)

Reducing character of hydrides of group 15 increases down the group

(b)

Basicity of hydrides of group 15 increases down the group

(c)

NCl5 does not exist

(d)

Phosphorus and arsenic can form P$\pi$-drt bond but not nitrogen

16. Sc( Z=21) is a transition element but Zinc (z=30) is not becaus

(a)

both Sc3+ and Zn2+ ions are colourless and form white compounds

(b)

in case of Sc, 3d orbital are partially filled but in Zn these are completely filled

(c)

last electron as assumed to be added to 4s level in case of zinc

(d)

both Sc and Zn do not exhibit variable oxidation states

17. When a brown compound of Mn (A) ids treated with HCl , it gives a gas (B) . The gas (B) taken in excess reacts with NH3 to give an explosive compound (C). The compound A, B and C are

(a)

MnO2, Cl2 , NCl3

(b)

MnO, Cl2 , NH4Cl

(c)

Mn3O4, Cl2 , NCl3

(d)

MnO3, Cl2 , NCl2

18. The reaction of aqueous KMnO4 with H2O2 in acidic condition gives

(a)

Mn4+ and MnO2

(b)

Mn4+ and O2

(c)

Mn2+ and O2

(d)

Mn2+ and O3

19. Value of magnetic moment of a divalent metal ion is, 5.92 BM. Total number of electron in its atom would be ______________

(a)

24

(b)

25

(c)

26

(d)

27

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. A complex has a molecular formula MSOCl. 6HO42.The aqueous solution of it gives white precipitate with Barium chloride solution and no precipitate is obtained when it is treated with silver nitrate solution. If the secondary valence of the metal is six, which one of the following correctly represents the complex?

(a)

[M(H2O)4Cl]SO42H2O

(b)

[M(H2O)6]SO4

(c)

[M(H2O)5Cl]SO4H2O

(d)

[M(H2O)3Cl]SO4.3H2O

22. Which one of the following pairs represents linkage isomers?

(a)

[Cu(NH3)4][ptCl4] and [pt(NH3)4][CuCl4]

(b)

[Co(NH3)5(NO3)]SO4 and [Co(NH3)5(ONO)]

(c)

[Co(NH3)4(NCS)2]ct and [Co(NH3)4(SCN)2]Cl

(d)

both (b) and (c)

23. The spin only magnetic moment of [Mnfsr4]2- is 5.9 BM. Geometry of the complex ion is

(a)

Tetrahedral

(b)

Octahedral

(c)

Square planar

(d)

Pentagonal pyramidal

24. Consider the following statements and identify the incorrect statement(s).
(i) CN- is a powerful ligand.
(ii) Haemoglobin is a monomer and myoglobin is a tetramer.
(iii) Cis - Pt (NH3)2Cl2 is an anti-tumor drug.

(a)

only (i)

(b)

only (ii)

(c)

only (iii)

(d)

both (i) and (iii)

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

(a)

Ca - EDTA

(b)

Cis - platin

(c)

Sodium thio sulphate

(d)

Nickel chloride

26. Graphite and diamond are

(a)

Covalent and molecular crystals

(b)

ionic and covalent crystals

(c)

both covalent crystals

(d)

both molecular crystals

27. In calcium fluoride, having the flurite structure the coordination number of Ca2+ ion and F- Ion are (NEET)

(a)

4 and 2

(b)

6 and 6

(c)

8 and 4

(d)

4 and 8

28. Crystalline solids are also called as

(a)

supercooled liquids

(b)

true solids

(c)

pseudo solids

(d)

all the above

29. In an hexagonal crystal

(a)

a=b=c,∝ =β=૪=90°

(b)

a=b=c,∝ =β=૪≠90°

(c)

a=b≠c,∝ =β=૪=90°

(d)

a=b≠c,∝ =β=90°૪=120°

30. The force that binds a metal ion to a number of electrons within its sphere. of influence is known as__________ bond.

(a)

covalent

(b)

ionic

(c)

metallic

(d)

co-ordinate

31. The addition of a catalyst during a chemical reaction alters which of the following quantities? (NEET)

(a)

Enthalpy

(b)

Activation energy

(c)

Entropy

(d)

Internal energy

32. In a first order reaction $x\longrightarrow y$ if k is the rate constant and the initial concentration of the reactant x is 0.1M, then, the half life is

(a)

$\left( \cfrac { log2 }{ k } \right)$

(b)

$\left( \cfrac { 0.693 }{ (0.1)k } \right)$

(c)

$\left( \cfrac { In2 }{ k } \right)$

(d)

none of these

33. For a reaction, 2A + B ⟶ 3C, The rate of appearance of C at time 't' is 1.2 x 10-4 mol L-1s-1. Identify the rate of reaction.

(a)

4 x10-5mol L-1s-1

(b)

4.5 x 10-1mol L-1s-1

(c)

3.6 x 10-4 mol L-1s-1

(d)

None of these

34. During a chemical reaction, the concentration of reaction

(a)

increases

(b)

decreases

(c)

remains constant

(d)

first increases and then decreases

35. CH3COOCH3 + H2 OH $\overset { { H }^{ + } }{ \longrightarrow }$ CH3 COOH + CH3 OH is an example of ____________ order reaction.

(a)

first

(b)

zero

(c)

third

(d)

pseudo

36. The solubility of BaSO4 in water is 2.42 ×10-3gL-1 at 298K. The value of its solubility product(Ksp) will be (Given molar mass of BaSO4 =233g mol 4-1)

(a)

1.08 ×10-14mol2L-2

(b)

1.08 ×10-12mol2L-2

(c)

1.08 ×10-10mol2L-2

(d)

1.08 ×10-8mol2L-2

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

(a)

BF3

(b)

PF3

(c)

CO

(d)

F

38. The condition for a compound to be precipitated is

(a)

Ionic product = solubility product

(b)

Ionic product < solubility product

(c)

Ionic product > solubility product

(d)

Ionic product ≤ solubility product

39. Which one of the following relationship is correct?

(a)

$pH=\frac { 1 }{ [{ H }^{ + }] }$

(b)

$pH={ log }_{ 10 }[{ H }^{ \\ + }]$

(c)

${ log }_{ 10 }pH=[{ H }^{ + }]$

(d)

$pH={ log }_{ 10 }\frac { 1 }{ [{ H }^{ + }] }$

40. According to ____________ concept, BF3 acts as a acid.

(a)

Bronsted

(b)

Arrhenius

(c)

Lewis

(d)

None of the above

41. Assertion : pure iron when heated in dry air is converted with a layer of rust.
Reason : Rust has the composition Fe3 O4

(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

42. The equivalent conductance of M/36solution of a weak monobasic acid is 6mho cm2 and at infinite dilution is 400 mho cm2. The dissociation constant of this acid is

(a)

1.25 ×10−6

(b)

6.25 x 10-6

(c)

1.25 ×10−4

(d)

6.25 x 10 -5

43. Kohlraush's law is applied to calculate

(a)

molar conductance at infinite dilution of a weak electrolyte

(b)

degree of dissociation of weak electrolyte

(c)

solubility of a sparingly soluble salt

(d)

all the above

44. The relationship between free energy change and emf of a cell is

(a)

∆G = -nFE

(b)

∆H = -nF

(c)

∆E = -nFG

(d)

∆F = -nFG

45. The zinc - copper cell has emf of ________

(a)

1V

(b)

2.1 V

(c)

1.1V

(d)

-1.1 V

46. Fog is colloidal solution 0 of

(a)

solid in gas

(b)

gas in gas

(c)

liquid in gas

(d)

gas in liquid

47. Which one of the is not a surfactant?

(a)

CH3 -(CH2)15 -N -(CH3)2 CH2Br

(b)

CH3 -(CH2)15 -NH2

(c)

CH3 -(- CH2- )-16CH2 OSO2- Na+

(d)

OHC-(CH2)14 -CH2 -COO- Na+

48. The phenomenon of scattering of light by the sol particles is called

(a)

tyndall effect

(b)

electrophoresis

(c)

cataphoresis

(d)

dialysis

49. Emulsifying agent used for O/W  emulsion is:

(a)

proteins

(b)

heavy metal salts of fatty acids

(c)

long chain alcohol

(d)

lamp black

50. The process of separation of emulsion into two separate layers is called___________

(a)

Emulsificatio

(b)

Deemulsification

(c)

Coagulation

(d)

Flocculation

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. The reactions

is an example of

(a)

Wurtz reaction

(b)

cyclic reaction

(c)

Williamson reaction

(d)

Kolbe reactions

53. Which one of the following has the highest boiling point?

(a)

CH3CH2CH2CH2CH3

(b)

CH3CH2CH2CH2OH

(c)

CH3CH2CH2CH3

(d)

CH3CH2CH2Cl

54. CH3CH2OH $\underset { (O) }{ \longrightarrow }$ CH3CHO  $\underset { (O) }{ \longrightarrow }$ CH3COOH To stop the oxidation reaction at the aldehyde stage, ______ is used as an oxidising agent.

(a)

KMnO4 | H+

(b)

K2Cr2O7 | H+

(c)

pyridinium chloro chromate

(d)

both (a) and (b)

55. Lower halogenated ethers can be converted into higher ethers by using _______ reagent.

(a)

Grignard

(b)

Tollen's

(c)

Fehling's

(d)

none of the above

56. Reaction of acetone with one of the following reagents involves nucleophilic addition followed by elimination of water. The reagent is

(a)

Grignard reagent

(b)

Sn / HCl

(c)

hydrazine in presence of slightly acidic solution

(d)

hydrocyanic acid

57. Which one of the following reaction is an example of disproporationation reaction

(a)

Aldol condensation

(b)

cannizaro reaction

(c)

Benzoin condensation

(d)

none of these

58. $HCHO+{ CH }_{ 3 }-\underset { \overset { || }{ O } }{ C } -{ CH }_{ 3 }\overset { dil }{ \underset { NaOH }{ \longrightarrow } } HO-{ CH }_{ 2 }-{ CH }_{ 2 }-\underset { \overset { || }{ \overset { O }{ 4-hydroxy\ butan-2-one } } }{ C } -{ CH }_{ 3 }$ is an example of _________ reaction.

(a)

Claisen Schmidt

(b)

Cannizaro

(c)

Aldol

(d)

Crossed aldol

59. Benzoin is _________.

(a)

an ∝ -hydroxy aldehyde

(b)

β- hydroxy aldehyde

(c)

β-hydroxy ketone

(d)

α - hydroxy ketone

60. Benzoic acid, when heated with soda lime gives _________.

(a)

C6H5COONa

(b)

C6H5COOC6H5

(c)

C6-C6

(d)

C6H5OH

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 some reducing agents used to convert Metal oxides to metal

65. What are the different methods of concentration of ores?

66. Boron does not react directly with hydrogen. Suggest one method to prepare diborane from BF3.

67. Give the structure of CO and CO2.

68. What is tetraethoxy silane? How is it obtained?

69. Among group 14 elements, name
(i) the most electro negative element
(ii) the most metallic element

70. Chalcogens belongs to p-block. Give reason.

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

72. How is nitrogen prepared from liquid air?

73. Give the reason for bleaching action of Cl2.

74. What are transition metals? Give four examples.

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

76. (i) Name the element showing maximum number of oxidation states among the first series of transition, metals from Sc (Z= 21) to Zn (Z=30).
(ii) Name the element which shows only +3 oxidation state.

77. What is hydroformylation of olefins?

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. [CuCl4]2- exists while [Cul4]2- does not exist why?

80. Write the IUPAC name of [Cu(NH3)4]SO4

81. Give the geometry and magnetic character of [NiCI4]2-

82. Why do solids have a definite volume?

83. A compound made up of two atoms X and Y has a face centred cubic arrangement. X is present in the coners and Y at the centre of each face. If one atom is missing from comer. What is the simplest formula of the compound.

84. Explain the rate determining step with an example.

85. Explain the effect of catalyst on reaction rate with an example

86. Why is instantaneous rate preferred over average rate?

87. A first order reaction has a specific reaction rate of 10-3 S-1. How much time will it take for 10gm of the reactant to reduce to 2.5 gm?

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

89. Calculate the pH of 0.001M HCl solution

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

91. Calculate the ionisation constant for the conjugate base of HF. Ionisation constant of HF at 298 K is 6.8 X 10-4

92. State Kohlrausch Law. How is it useful to determine the molar conductivity of weak electrolyte at infinite dilution.

93. Describe the electrolysis of molten NaCl using inert electrodes

94. Name the anode, cathode and electrolyte used in lithium - ion Battery

95. Explain how iron is protected from corrosion by coating with magnesium.

96. What is the formula for Ziegler - Natta catalyst?

97. What are promoters? Give an example.

98. How will you convert of ethylene glycol to 1,4 - dioxane.

99. State Saytzeff's rule.

100. Acetone is soluble in water but benzophenone is not. Give reason.

101. Explain HVZ reaction.

102. Part - C

22 x 3 = 66
103. Give the uses of zinc.

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

105. Write a short note on hydroboration

106. How is aluminum chloride prepared from aluminum?

107. Write the reason for the anamolous behaviour of Nitrogen.

108. What is Haber's process? (or) How is ammonia synthesized by Haber's process?

109. Which is more stable? Fe3+ or Fe2+ - explain.

110. Give reason for the following:
(i) A transition metal exhibits highest oxidation state in oxides and fluorides.
(ii) Cu2+ is unstable in an aqueous solution.

111. In an octahedral crystal field, draw the figure to show splitting of d orbitals

112. Draw the structures of geometrical isomers of [Fe(NH3)2 (CN)4]-

113. Inspite of long range order in the arrangement of particles, why are the crystals usually not perfect?

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. The rate constant for a first order reaction is 60 S-1. How much time will it take to reduce the initial concentration of the reactant to its ${ \frac { 1 }{ 16 } }^{ th }$ value?

116. 50ml of 0.05M HNO3 is added to 50ml of 0.025M KOH. Calculate the pH of the resultant solution.

117. Based on Arrhenius concept, defme acid and bases and give an example for each.

118. A current of 1.608A is passed through 250 mL of 0.5M solution of copper sulphate for 50 minutes. Calculate the strength of Cu2+ after electrolysis assuming volume to be constant and the current efficiency is 100%.

119. What is the oxidation and reduction half cell in a Daniel cell?

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

122. Explain the manufacture of glycerol from triglycerides,

123. Give the Grignard reagent and carbonyl compound that can be used to prepare.
(a) CH3-CH2-CH2-OH
(b) (CH3)2C(OH)CH2CH2CH3
(c) C6H5CH2CH(OH)CH3

124. Formaldehyde and benzaldehyde give Cannizaro reaction but acetaldehyde does not - account for this.

125. Part - D

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

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

128. Explain the bleaching action of Chlorine.

129. Why is there a variation of atomic andionic size as we move from Sc to Zn?

130. Indicate the types of isomerism exhibited by the following complexes and draw the structures for these isomers.
(i) K[Cr(H2O)2 (C2O4)2] (ii) [Co(en)3]CI3 (iii) [Co(NH3)5(NO2)](NO3)2
(iv) [Pt (NH3)(H2O)CI2]

131. How can you determine the atomic mass of an unknown metal if you know its density and the dimension of its unit cell? Explain.

132. Reaction is first order in A and second in B.
(i) Write the different rate equation.
(ii) How is the rate affected on increasing the concentration of B three times?
(iii) How is the rate affected when the concentrations of both A and Bare doubled?

133. A 0.02 M solution of a weak mono basic acid is 5% ionised. Calculate the ionisation constant of the acid.

134. Specific conductance of 1M KNO3 solution is oberved to be 5.55 x 10-3 mho cm2. What is the equivalent conductance of KNO3 when one litre of the solution is used?

135. Explain the factors affecting adsorption.

136. Distinguish between (a) Ethanol and phenol (b) Phenol and acetic acid (c) Phenol and aniline (d) Phenol and anisole.

137. An organic compound (A) with molecular formula C3H6O undergoes iodoform reaction. Two molecules of compound (A) react with dry HCI to give compound (B) (C6H10O). Compound (B) reacts with one more molecule of compound (A) to give compound (C) (C9H14O). Identify (A), (B) and (C). Explain the reactions.