" /> -->

#### Important Questions Part-VI

12th Standard EM

Reg.No. :
•
•
•
•
•
•

Chemistry

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

Part - A

60 x 1 = 60
1. Wolframite ore is separated from tinstone by the process of

(a)

Smelting

(b)

Calcination

(c)

Roasting

(d)

Electromagnetic separation

2. Zinc is obtained from ZnO by

(a)

Carbon reduction

(b)

Reduction using silver

(c)

Electrochemical process

(d)

Acid leaching

3. Among the following, one does not belong to calcination, Pick the odd one out.

(a)

${ PBCO }_{ 3 }\overset { \Delta }{ \longrightarrow } PBO+{ CO }_{ 2 }\uparrow$

(b)

${ CaCo }_{ 3 }\overset { \Delta }{ \longrightarrow } Cao+{ CO }_{ 2 }\uparrow$

(c)

$PbS{ O }_{ 3 }\overset { \Delta }{ \rightarrow } PbO+{ 2SO }_{ 2 }\uparrow$

(d)

${ ZnCO }_{ 3 }\overset { \Delta }{ \rightarrow } ZnO+{ CO }_{ 2 }\uparrow$

4. Zinc is extracted from Zinc blende by_________

(a)

Carbon reduction process

(b)

Nitrogen reduction process

(c)

Oxygen reduction process

(d)

All of these

5. Na[Ag(CN)2] is _________.

(a)

Sodium aurocyanide

(b)

Sodium meta aluminate

(c)

Aluminosilicate

(d)

Sodium dicyano argentate

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. The stability of +1 oxidation state increases in the sequence

(a)

Al < Ga < In < Tl

(b)

Tl < In < Ga < Al

(c)

In < Tl < Ga < Al

(d)

Ga< In < Al < Tl

8. SiO44- ion has ____ geometry.

(a)

Triangular

(b)

Tetrahedral

(c)

Linear

(d)

Pentagonal bipyramidal

9. In graphite electrons are

(a)

localised on each C-atom

(b)

localised on every third C-atom

(c)

delocalised within the layer

(d)

present in anti-bonding orbital

10. Allotropy is due to ______

(a)

difference in chemical properties

(b)

difference in the number of atoms in the molecules

(c)

difference in the arrangement of atoms in the molecules in the crystal

(d)

None of these

11. Solid (A) reacts with strong aqueous NaOH liberating a foul smelling gas(B) which spontaneously burn in air giving smoky rings. A and B are respectively

(a)

P4(red) and PH3

(b)

P4(white) and PH3

(c)

S8 and H2S

(d)

P4(white) and H2S

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. Which of the following is correct?

(a)

H3PO3 is dibasic and reducing

(b)

H3PO3 is dibasic and non-reducing

(c)

H3PO4 is tribasic and reducing

(d)

H3PO3 is tribasic and non-reducing

14. Thr hybridisation and shape of SF6 is respectively?

(a)

sp3d2,square planar

(b)

sp3d2,octahedral

(c)

sp3d see-saw

(d)

sp3d,trigonal bipyramindal

15. Pick the wrong one among the following

(a)

F2 - Yellow

(b)

Br2 - Red

(c)

Cl2 - Colourless

(d)

I2- Violet

16. Which of the following does not give oxygen on heating?

(a)

K2Cr2O7

(b)

(NH4)2Cr2O7

(c)

KClO3

(d)

Zn(ClO3)2

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. 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. CrO3 is coloured due to

(a)

Low l.E

(b)

Crystal defects

(c)

Charge transfer spectra

(d)

Unpaired electrons

20. FeSO4 on heating gives ____________

(a)

SO2 and O2

(b)

SOand SO3

(c)

SO2

(d)

SO3

21. How many geometrical isomers are possible for<<EVA035.eps>>?

(a)

3

(b)

4

(c)

0

(d)

15

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. A metal ion from the first transition series forms an octahedral complex with magnetic moment of 4.9 BM and another octahedral, complex which is diamagnetic. The metal ion is

(a)

Fe2+

(b)

Co2+

(c)

Mn2+

(d)

Ni2+

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. Crystal field stabilization energy for high spin d4 octahedral complex is _____________

(a)

- 0. 6 ${ \triangle }_{ 0 }$

(b)

- 1. 8 ${ \triangle }_{ 0 }$

(c)

- 1. 6 ${ \triangle }_{ 0 }$

(d)

- 1. 4 ${ \triangle }_{ 0 }$

26. The cation leaves its normal position in the crystal and moves to some interstitial position, the defect in the crystal is known as

(a)

Schottky defect

(b)

F center

(c)

Frenkel defect

(d)

non-stoichiometric defect

27. The crystal with a metal deficiency defect is

(a)

NaCl

(b)

FeO

(c)

ZnO

(d)

KCl

28. A solid with formula ABC3 would probably have,

(a)

A at body centre, B at face centres and C at corners of the cube

(b)

A at corners of cube, B at body centre, C at face centre

(c)

A at corners of hexagon, B at centres of the hexagon and C inside the hexagonal unit cell

(d)

A at corner, B at face centre, C at body centre

29. The empty space between the shaded balls and hollow balls as shown in the diagram is called,

(a)

Hexagonal void

(b)

Octahedral void

(c)

Tetrahedral void

(d)

Double triangular void

30. Iodine crystals are __________.

(a)

covalent

(b)

ionic

(c)

metallic

(d)

molecular

31. For a first order reaction A ⟶ product with initial concentration x mol L-1, has a half life period of 2.5 hours. For the same reaction with initial concentration $\left( \frac { x }{ 2 } \right)$ mol L-1 the half life is

(a)

(2.5 x 2) hours

(b)

$\left( \frac { 2.5 }{ 2 } \right)$hours

(c)

2.5 hours

(d)

Without knowing the rate constant, t1/2 cannot be determined from the given data

32. For a reaction Rate = kacetone[]32 then unit of rate constant and rate of reaction respectively is

(a)

(mol L-1 S-1),(mol1/2L1/2S-1)

(b)

(mol-1/2L1/2s-1),(mol L-1s-1)

(c)

(mol1/2L1/2s-1),(molL-1s-1)

(d)

(molLs-1),(mol1/2L1/2s)

33. For a reaction: aA ⟶ bB, the rate of reaction is doubled when the concentration of A is increased by four times. The rate of reaction is equal to

(a)

k[A]a

(b)

$k{ \left[ A \right] }^{ \frac { 1 }{ 2 } }$

(c)

$k{ \left[ A \right] }^{ \frac { 1 }{ a } }$

(d)

K[A]

34. For the reaction N2(g) + 3H2(g) ⟶ 2NH3(g) the rate of the reaction in terms of ammonia is __________________

(a)

$+\frac { 1 }{ 2 } \frac { -d\left[ { NH }_{ 3 } \right] }{ dt }$

(b)

$-\frac { 1 }{ 2 } \frac { d\left[ { NH }_{ 3 } \right] }{ dt }$

(c)

$\frac { -d\left[ { NH }_{ 3 } \right] }{ dt }$

(d)

$\frac { +d\left[ { NH }_{ 3 } \right] }{ dt }$

35. The half-life period of a first order reaction is 69.3 seconds. Its rate constant is _______________.

(a)

10-2 s-1

(b)

10-4 s-1

(c)

10 s-1

(d)

102 s-1

36. What is the decreasing order of strength of bases
OH, NH2- H - C ≡ C and CH3 - CH2-

(a)

OH->NH2- >H-C≡C >CH3-CH2-

(b)

NH2->OH->CH3-CH2- >H-C≡C

(c)

CH3-CH2->NH2->H-C≡C->OH-

(d)

OH->H-C ≡ C->CH3-CH2- >NH2-

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. Krepresents

(a)

ionic product constant of water

(b)

Solubility product of water

(c)

Equilibrium constant of water

(d)

Buffer index

39. For two acids A and B, Ka values at 25°C are 2 x 106 and 1.8 x 10-4 respectively. which among the following is true with respect to the above data.

(a)

A and B are equally acidic

(b)

A is stronger than B

(c)

B is stronger than A

(d)

Ka value is not a measure of acid strength

40. NH4OH is a weak base because

(a)

it has low vapour pressure

(b)

it is only partially ionised

(c)

it is completely ionised

(d)

it has low densit

41. 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

42. A gas X at 1 atm is bubble through a solution containing a mixture of 1MY- and 1MZ- at 25oC . If the reduction potential of Z>Y>X, then

(a)

Y will oxidize X and not Z

(b)

Y will oxidize Z and not X

(c)

Y will oxidize both X and Z

(d)

Y will reduce both X and Z

43. The important use of Kohlrausch's law is deducing the

(a)

λ value of weak electrolyte.

(b)

λ value of strong electrolyte.

(c)

λ value of weak electrolyte.

(d)

λ value of weak electrolyte

44. What is/are the factor(s) that govern the single electrode potential of a half cell?

(a)

concentration of ions in solution

(b)

tendency to form ions

(c)

temperature

(d)

all of these

45. In an electrochemical cell, the wrong statement is

(a)

electrons move from cathode to anode

(b)

anode is negative charged

(c)

cathode is positive charged

(d)

chemical energy is converted to electrical energy.

46. The most effective electrolyte for the coagulation of AS2S3Sol is

(a)

NaCl

(b)

Ba(NO3)2

(c)

K3[Fe(CN)6]

(d)

Al3+

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. The impurity present in the colloidal particle is

(a)

electrolytes

(b)

solute

(c)

both (a) and (b)

(d)

neither (a) or (b)

49. In W/O system, the dispersion medium is_______

(a)

water

(b)

benzene

(c)

alcohol

(d)

oil

50. Decomposition of hydrogen peroxide is retarded in the presence of________

(a)

alcohol

(b)

glycerine

(c)

MnO2

(d)

Mo

51. The X is

(a)

(b)

(c)

(d)

None of these

52. Among the following ethers which one will produce methyl alcohol on treatment with hot HI?

(a)

(H3C)-3C-|-O-CH3

(b)

(CH3-)2-CH-CH2-O-CH3

(c)

CH3-(CH2)3-O-CH3

(d)

CH3-CH2-$\underset { \overset { | }{ { CH }_{ 3 } } }{ CH }$-O-CH3

53. An example of trihydric alcohol is _________

(a)

trimethyl carbinol

(b)

3-hexanol

(c)

propane-1,2,3-triol

(d)

tert-butylacohol

54. CH3-CH2-O-CH2CH3 and ${ CH }_{ 3 }-O-\overset { \underset { | }{ { CH }_{ 3 } } }{ CH } -{ CH }_{ 3 }$ are examples of _______ isomerism.

(a)

functional

(b)

chain

(c)

position

(d)

metamerism

55. _______ cannot be prepared by using Grignard reagent.

(a)

CH3- OC2H5

(b)

CH3-OCH3

(c)

C2H5-O-C2H5

(d)

CH3-OCH2CH2CH3

56. In which case chiral carbon is not generated by reaction with HCN

(a)

(b)

(c)

(d)

57. An alkene “A” on reaction with O3 and Zn - H2O gives propanone and ethanol in equimolar ratio. Addition of HCl to alkene “A” gives “B” as the major product. The structure of product “B” is

(a)

$Cl-{ CH }_{ 2 }-CH_{ 2 }-\overset { \overset { CH_{ 3 } }{ | } }{ \underset { \underset { CH_{ 3 } }{ | } }{ CH } }$

(b)

${ H }_{ 3 }C-{ CH }_{ 2 }-\overset { \overset { CH_{ 2 }Cl }{ | } }{ CH } -{ CH }_{ 3 }$

(c)

$\\ { H }_{ 3 }C-{ CH }_{ 2 }-\overset { \overset { CH_{ 3 } }{ | } }{ \underset { \underset { CH_{ 3 } }{ | } }{ C } } -{ CH }_{ 3 }$

(d)

${ H }_{ 3 }C-{ CH }-\overset { \overset { CH_{ 3 } }{ | } }{ \underset { \underset { Cl }{ | } }{ C } }$

58. When propanoic acid is treated with aqueous sodium-bicarbonate, CO2 is liberated. The "C" of CO comes from

(a)

methyl group

(b)

carboxylic acid group

(c)

methylene group

(d)

bicarbonate

59. Chloroacetic acid is stronger than acetic acid due to

(a)

+ I effect

(b)

- I effect

(c)

+M effect

(d)

-M effect

60. Lower members of carboxylic acid family are

(a)

waxy solids

(b)

pleasant smelling liquids

(c)

foul smelling liquids

(d)

inert gases

61. Part - B

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

63. What is the role of Limestone in the extraction of Iron from its oxide Fe2O3?

64. Why should we have a ecofriendly metallurgical process?

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

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

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

68. What are alums?

69. Starting from Sicl4, prepare the following in steps not exceeding the number given in parentheses.
(i) Silicon
(ii) Linear silicon containing methyl groups only
(iii) Na2SiO3

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

71. Give the uses of helium.

72. What is the reaction of Phosphorous with alkali?

73. Acidic character increases from HF to HI. I State whether the above statement is True or false and give reason for your answer.

74. What are actinides? Give three example

75. Why Gd3+ is colourles?

76. Which is the most common oxidation state of lanthanoides?

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

78. 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 $[Ag(NH_{ 3 })_{ 2 }]^{ \rightarrow }$

79. Based on VB theory explain why [Cr(NH3)6]3+ is paramagnetic, while [Ni(CN)4]2- is diamagnetic.

80. Write a neutral molecule in which the central atom is Sp3 d2 hybridised.

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

82. Why do solids have a definite volume?

83. What is the total number of atoms per unit cell in a face - centered cubic structure (fcc)?

84. Define average rate and instantaneous rate

85. Explain the rate determining step with an example.

86. 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.

87. In a reaction, 2A $\longrightarrow$ products, the concentration of A decreases from 0.5 mol L-1 to 0.4 mol L-1 in 10 minutes. Calculate the rate during this interval?

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

89. Define solubility product

90. Give a condition for a compound to be precipitated.

91. BF3 is termed as an acid though it does not contain H+ ions. Explain.

92. Describe the construction of Daniel cell. Write the cell reaction.

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. On dilution of 0.1 M of Na2SO4, what will happen to its
a) Conductance (C)
(b) Conductivity K
(c) Molar conductance Am
(d) Equivalent conductance ${ \Lambda }_{ m }$

95. Why is the electrode potential of a single electrode cannot be determined?

96. What is Ultrafilteration?

97. What is difference between sol) gel and emulsion?

98. Identify the product A and B.

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

100. Complete the following reaction

101. Write a note on Claisen Condensation.

102. Part - C

22 x 3 = 66
103. Explain zone refining process with an example using the Ellingham diagram given below

104. What is cementation?

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

106. Describe the structure of diamond.

107. Give the balanced equation for the reaction between chlorine with cold NaOh and hot NaOH.

108. Explain the reaction of ammonia with chlorine and chlorides at different conditions

109. Explain the variation in E0M3+/M2+  3d series.

110. Explain why oxidation states of transition elements increases first from Sc to Mn and then decrease?

111. Give one test to differentiate [Co(NH3)5Cl]SO4 and [Co(NH3)5SO4]Cl.

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. Answer the following:
(I) Name the intermolecular force present in ice.
(II) What type of bond is present in network solid?

114. Explain briefly the collision theory of bimolecular reactions

115. The energy of achivation for the formation of hydrogen iodide is 150 kJ mol-1 The rate constant of this reaction at 673 K is 2.3 X 10-3. Calculate the rate constant at 773 K.

116. Derive an expression for Ostwald’s dilution law

117. What do you mean by buffer action?

118. Can Fe3+ oxidises Bromide to bromine under standard conditions?
Given: ${ E }_{ { Fe }^{ 3+ }|{ Fe }^{ 2+ } }^{ 0 }=0.771$
$\\ { E }_{ { Br }_{ 2 }|{ Br }^{ - } }=1.09V$.

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

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

121. What are the advantages of Brownian movement?

122. What happens when 1-penyl ethanol is treated with acidified KMnO4.

123. Ethers should not be heated to dryness. Why? (OR) How does diethyl ether react WIith oxygen.?

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

125. Part - D

12 x 5 = 60
126. Write short note on the following:
(i) The process in which no external reducing agent is used.
(ii) The process which is used for highly electro positive metal.
(iii) Write the equation involved in the thermite process.

127. Distinguish between diamond and graphite.

128. An amorphous solid (A) burns in air to form a gas (B)which turns lime water milky. The gas is also produced as a byproduct during roasting of sulphide ore. This gas decolourises acidified aqueous KMnO4 solution and reduces Fe3+ to Fe2+. Identify the solid 'A' and the gas 'B' and write the reactions involved.

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

130. Give the postulates and limitation of Werner's theory of co-ordination compounds.

131. What are the general characteristics of solids?

132. The initial rate of a first order reaction is 5.2 x 10-6 mol lit-1 S-1 at 298 K. When the initial concentration of reactant is 2.6 x 10-3 mol.lit-1, calculate the first order rate constant of the reaction at the same temperature.

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

134. The equilibrium constant of cell reaction: Ag(s) + Fe3+ ⇌ Fe2+ + Ag+ is 0.335 at 25°C. Calculate the standard emf of the cell AgI Ag+; Fe3+, Fe2+. Calculate Eo of the half cell Fe3+, Fe2+/Pt is 0.7791 V Calculate Eo of Fe3+, Fe2+/ Pt half cell.

135. Write a note on phase transfer catalysis.

136. Compound (A) with molecular formula C6H6O gives violet colour with neutral FeCI3 (A) reacts with CHCl3 and NaOH gives two isomers (B) and (C) with molecular formula C7H6O2 Compound (A) reacts with ammonia at 473 K in the presence of ZnCl2 gives compound (D) with molecular formula C6H7N. Compound (D) undergoes carbylamine test. Identify (A), (B), (C) and (D) and explain the reactions.

137. An organic compound (A) of molecular formula C7H6O is not reduced by Fehling's solution but will undergo Cannizzaro reaction. Compound (A) reacts with aniline to give compound (B). Compound (A) also reacts with Cl2 in the presence of catalyst to give compound (C). Identify (A (B) and (C) and explain the reactions.