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#### Important Questions Part-IX

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 following statements, about the advantage of roasting of sulphide ore before reduction is not true?

(a)

$\Delta { G }_{ f }^{ 0 }$ of sulphide is greater than those for CS2 and H2S

(b)

$\Delta { G }_{ r }^{ 0 }$ is negative for roasting of sulphide ore to oxide

(c)

Roasting of the sulphide to its oxide is thermodynamically feasible

(d)

Carbon and hydrogen are suitable reducing agents for metal sulphides

2. Which of the following reduction is not thermodynamically feasible?

(a)

${ Cr }_{ 2 }{ O }_{ 3 }+2Al\longrightarrow { Al }_{ 2 }{ O }_{ 3 }+2Cr$

(b)

${ Al }_{ 2 }{ O }_{ 3 }+2Cr\longrightarrow { Cr }_{ 2 }{ O }_{ 3 }+2Sl$

(c)

$3Ti{ O }_{ 2 }+4Al\longrightarrow 2A{ l }_{ 2 }{ O }_{ 3 }+3Ti$

(d)

none of these

3. $2PbS+{ 3O }_{ 2 }\longrightarrow 2pbO+{ 2SO }_{ 2 }$ Name the process

(a)

Roasting

(b)

Calcination

(c)

Smelting

(d)

Leaching

4. Ignition mixture used in aluminothermite process is

(a)

Cr + AI2O3

(b)

Mg + BaO2

(c)

AI + Cr2O3

(d)

Ba+MgO

5. Magnesite is_________

(a)

Magnesium oxide

(b)

Magnesium carbonate

(c)

Magnesium sulphate

(d)

Magnesium chloride

6. The geometry at which carbon atom in diamond are bonded to each other is

(a)

Tetrahedral

(b)

graphene

(c)

Fullerene

(d)

dry ice

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. Lewis acid character of boron trihalides is as a follows:

(a)

BF3 > BCl3 > BBr3 > BI3

(b)

BCI> BF3 > BBr3 > BI3

(c)

BI3 > BBr3 > BCl3 > BF3

(d)

BI3 > BF3 > BCl3 > BBr3

9. Which one is correct statement for zeolite?

(a)

Zeolites are aluminosilicates having three dimensional framework

(b)

Hydrate zeolites are used as ion exchangers in hardening of soft water

(c)

Zeolites are alumino silicates

(d)

all the above

10. Borax is _______

(a)

Na2[B4O5(OH)4).8H2O

(b)

Na2[B4O5(OH)6).7H2O

(c)

Na2[B4O3(OH)8].6H2O

(d)

Na2[B4O2(OH)10).5H2O

11. Among the following, which is the strongest oxidizing agent?

(a)

Cl2

(b)

F2

(c)

Br2

(d)

l2

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

(a)

S4O62-

(b)

S2O62-

(c)

SO42-

(d)

SO32-

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. Allotrope of sulphur which shows paramagnetic behaviour

(a)

S8- Rhombic

(b)

S8- Monoclinic

(c)

S2- In vapour phase

(d)

Not possible

15. Orthophosphorus acid on heating gives________

(a)

Hypophosphorus

(b)

Orthophosphoric acid

(c)

Phosphine gas

(d)

both (b) and (c)

16. Which of the following compounds is colourless?

(a)

Fe3+

(b)

Ti4+

(c)

Co2+

(d)

Ni2+

17. MnO4- react with Br- in alkaline PH to give

(a)

BrO3- MnO2

(b)

Br2, MnO42-

(c)

Br2, MnO2

(d)

BrO-, MnO42-

18. Except ______________ all element from Rf to Cn, are synthetically prepared and have very low half life periods.

(a)

(b)

actinium

(c)

yttrium

(d)

19. Of these statement, which statement is incorrect in most of the transition elements are _____________

(a)

hexagonal close packed

(b)

cubic close packed

(c)

face centered cubic

(d)

symmetrical distribution

20. If the standard electrode potential (Eo) of a inetal is ____________ and ______________ the metal is a powerful reducing agent.

(a)

large, negative

(b)

large, positive

(c)

small, negative

(d)

small, positive

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 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. Co-ordination isomerism is exhibited by

(a)

[Cr(en)2Cl2]NO2

(b)

[Pt(NH3)4] [CuCl4]

(c)

[Cr(en)2Cl2]NO

(d)

[Co(NH3)5Cl]Cl2

24. Which of the following is wrong about double salts?

(a)

retain their properties only in solid state

(b)

contains two or more salt in stoichiometric proportions

(c)

they don't dissociate into its constituent ions

(d)

none of the above

25. ______________ valencies are directional in nature.

(a)

primary

(b)

secondary

(c)

teriary

(d)

None

26.  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)

$\cfrac { 1 }{ 2 } a:\sqrt { 3 } a:\cfrac { 1 }{ \sqrt { 2 } } a$

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. Pick out the example for covalent and molecular crystal.

(a)

Ice,Diamond

(b)

Diamond,Ice

(c)

NaCl, FeS

(d)

FeS,Ice

29. Which one of the following is a network solid?

(a)

diamond

(b)

silicon carbide

(c)

naphthalene

(d)

both (a) and (b)

30. The coordination number of a metal crystallising in a hexagonal close packed structure is __________

(a)

6

(b)

4

(c)

8

(d)

12

31. For a first order reaction A ⟶ B the rate constant is x min−1. If the initial concentration of A is 0.01M , the concentration of A after one hour is given by the expression.

(a)

001. e−x

(b)

1 x 10-2(1-e-60x)

(c)

(1x10-2)e-60x

(d)

none of these

32. The decomposition of phosphine (PH3) on tungsten at low pressure is a first order reaction. It is because the (NEET)

(a)

rate is proportional to the surface coverage

(b)

rate is inversely proportional to the surface coverage

(c)

rate is independent of the surface coverage

(d)

rate of decomposition is slow

33. What would be the activation energy of a reaction when the temperature is increased from 27oC to 37oC?

(a)

534 kJ mol-1

(b)

53.4 kJ mol-1

(c)

5.34 kJ mol-1

(d)

None of these

34. Which of the following does not affect the rate of reaction?

(a)

Amount of the reactant taken

(b)

Physical state of the reactant

(c)

∆H of reaction

(d)

Size of vessel

35. The excess energy which a molecule must possess to become active is known as

(a)

kinetic energy

(b)

threshold energy

(c)

potential energy

(d)

activation energy

36. Concentration of the Ag+ ions in a saturated solution of Ag2C2O4 is 2.24 ×10-4mol L-1 solubility product of Ag2C2O4 is

(a)

2.42 ×10-8mol3L-3

(b)

2.66 ×10-12mol3L-3

(c)

4.5 ×10-11mol3L-3

(d)

5.619 ×10-12mol3L-3

37. Which will make basic buffer?

(a)

50 mL of 0.1M NaOH+25mL of 0.1M CH3 COOH

(b)

100 mL of 0.1M CH3COOH+100 mL of 0.1M NH4OH

(c)

100 mL of 0.1M HCl+200 mL of 0.1M NH4OH

(d)

100 mL of 0.1M HCl+100 mL of 0.1M NaOH

38. 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

39. The degree of hydrolysis of 0.1 M solution of ammonium acetate is 8.48 x 10-5. The dissociation constant of the weak base is

(a)

1.39 x 10-4

(b)

1.39 X 10-5

(c)

1.45 X 10-10

(d)

1.45 X 10-9

40. In the complex, between boron tri fluoride and ammonia BF3 ⇽NH3, BFis ________

(a)

elodron deficient

(b)

electron pair donor

(c)

Lewis acid

(d)

elodron deficient and Lewis acid

41. Zinc can be coated on iron to produce galvanized iron but the reverse is not possible. It is because

(a)

Zinc is lighter than iron

(b)

Zinc has lower melting point than iron

(c)

Zinc has lower negative electrode potential than iron

(d)

Zinc has higher negative electrode potential than iron

42. Consider the change in oxidation state of Bromine corresponding to different emf values as shown in the diagram below:
${ BrO }_{ 4 }^{ - }\overset { 1.82V }{ \longrightarrow } { BrO }_{ 3 }^{ - }\overset { 1.5V }{ \longrightarrow } HBrO\overset { 1.595v }{ \longrightarrow } { Br }_{ 2 }\overset { 1.0652V }{ \longrightarrow } Br$
Then the species undergoing disproportional is

(a)

Br2

(b)

BrO4-

(c)

BrO-3

(d)

HBrO

43. 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

44. What will be the equilibrium constant for the reaction between AgNO3 and metallic Zn, where Eocell = 1.56V?

(a)

6.19 x 1052

(b)

619 X 1052

(c)

0.619 X 1025

(d)

6.19 X 1025

45. The maximum work that can be derived from a chemical reaction is

(a)

Wmax = ΔH

(b)

Wmax = ΔG

(c)

Wmax = ΔE

(d)

Wmax = ΔS

46. The coagulation values in millimoles per litre of the electrolytes used for the coagulation of AS2S3 are given below
(I) (NaCl)=52 (II) ((BaCl2)=0.69 (III) (MgSO4)=0.22
The correct order of their coagulating power is

(a)

III > II > I

(b)

I > II > III

(c)

I > III > II

(d)

II > III>I

47. If x is the amount of adsorb ate and m is the amount of adsorbent, which of the following relations is not related to adsorption process?

(a)

x/m=f(P) at constant T

(b)

x/m=f(T) at constant P

(c)

P = f(T) at constant x/m

(d)

x/m = PT

48. Oil soluble dye is mixed with emulsion and emulsion remains colourless then, the emulsion is

(a)

O/W

(b)

W/O

(c)

O/O

(d)

W/W

49. Colloids are purified by

(a)

precipitation

(b)

coagulation

(c)

dialysis

(d)

filtration

50. Peptisation is not used to prepare

(a)

silverchloridesol

(b)

ferric hydroxide sol

(c)

both (a) and (b)

(d)

colloidal platinum

51. 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

52. On reacting with neutral ferric chloride, phenol gives

(a)

red colour

(b)

violet colour

(c)

dark green colour

(d)

no colouration.

53. On oxidation of an alcohol gives an aldehyde having the same number of cabon atoms as that of alcohol is ________

(a)

10 alcohol

(b)

20 alcohol

(c)

30 alcohol

(d)

None

54. The test used to distinguish wish 10, 20 and 30 alcohol is ________

(a)

Lucas test

(b)

Victor Meyer's

(c)

dehydrogenation

(d)

all the above

55. The IUPAC name of phenetole is __________

(a)

ethoxybenzene

(b)

methyl phenyl ether

(c)

diethyl ether

(d)

diphenyl ether

56. Identify the product formed in the reaction

(a)

(b)

(c)

(d)

57. Assertion : p – N, N – dimethyl aminobenzaldehyde undergoes benzoin condensation
Reason : The aldehydic (-CHO) group is meta directing

(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

58. Aldehydes may be distinguished from ketones by the use of

(a)

conc. H2SO4

(b)

Fehling's solution

(c)

pyrogallol

(d)

Lucas reagent

59. Which of the following compounds will react with NaHCO3 solution to give sodium salt and CO2?

(a)

Acetic acid

(b)

n-Hexanol

(c)

Phenol

(d)

Both (A) and (c)

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 is the difference between minerals and ores?

63. What are the various steps involved in extraction of pure metals from their ores?

64. List out the commercial uses of iron.

65. Give reason : Extraction of copper directly from sulphide ores is less favourable than from its oxide ores through reduction.

66. Write a note on Fisher tropsch synthesis

67. Give the structure of CO and CO2.

68. Explain the formation of boron trifluoride.

69. What happens to CO2 when dissolved in water?

70. What are interhalogen compounds? Give examples.

71. Why fluorine is more reactive than other halogens?

72. How would you account for the following? The electron gain enthalpy with negative sign is less for oxygen than that of sulphur.

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

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

75. Justify the position of lanthanides and actinides in the periodic table.

76. Orange colour of Cr2O72- ion charges to yellow in alkali and yellow solution turns out orange on adding H+ ions. Explain why?

77. What are the conditions for alloy formation?

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. What is a central atom or ion?

81. Draw the Cis and trans isomer of MA2B2 type

82. Name the seven primitive crystal systems.

83. A compound forms hexagonal dosed packed structure. What is the total number of voids in 0.5 mol of it? How many of these are tetrahedral voids?

84. Describe the graphical representation of first order reaction.

85. The decomposition reaction of ammonia gas on platinum surface has a rate constant R = 2.5 X 10-4mol L-1. What is the order of the reaction.

(i) Effect the adding catalyst on activation energy and Gibb's energy (ΔG).
(ii) Why do we heat the solution of oxalic acid in redox tetration against KMnO4?

87. The rate of the reaction X+2y⇾ product is 4x10-3 mol L-1S-1, if [X]=[Y]=0.2M and rate constant at 400K is 2x10-2s-1, What is the overall order of the reaction

88. Define solubility product

89. Calculate the concentration of OH- in a fruit juice which contains $2\times10^{-3}$ M, H3O+ ion. Identify the nature of the 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. Why does conductivity of a solution decrease on dilution of the solution

93. A conductivity cell has two platinum electrodes separated by a distance 1.5 cm and the
cross sectional area of each electrode is 4.5 sq cm. Using this cell, the resistance of 0.5 N electrolytic solution was measured as 15 Ω . Find the specific conductance of the solution.

94. What is the value of Faraday constant? Define it.

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

96. Define Deemulsification.

97. Name the factors that affect adsorption.

98. Explain 'esterification' reaction with an example.

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

100. Ethanal is more reactive towards nucleophilic addition reaction than propanone.Why?

101. Name a chemical test to distinguish between the following.
(i) 2-Pentanone, 3- Pentanone
(ii) Acetone, acetaldehyde
(iii) Benzaldehyde, butanal

102. Part - C

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

104. How is acid leaching done for the sulphide ores?

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. How is boron trifluoride obtained from boron trioxide?

107. Write the valence shell electronic configuration of group-15 elements.

108. Complete the following reactions
(l) Cl2+ H20$\longrightarrow$?
(ii) XeF6 + 2H20 $\longrightarrow$ ?
(Iii) XeF6 + 2H20$\longrightarrow$?

109. Compare lanthanides and actinides

110. What happens to KMnO4 when it reacts with
(i) Cold Cone. H2SO4
(ii) hot Cone H2SO4?

111. Write the postulates of Werner’s theory

112. Match the common name with formula and the IUPAC ligand name.

Common name Formula IUPAC ligand name
Bromide C2O42- Carbonato
Nitrate Br- Oxalato
hydroxide NO3- hydroxido
Carbonate OH- bromido
Oxalate CO32- nitrato
113. How do the spacings of the three planes (100), (101) and (111) of simple cubic lattice vary?

114. 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.

115. A reaction is second order with respect to a reactant. How is the rate of reaction affected if the concentration of the reactant is
(i) doubled (ii) reduced to half

116. Explain common ion effect with an example

117. How will you calculate solubility product from molar solubility?

118. Reduction potential of two metals M1 and M2 are $E^{0}_{M^{2+}_{1}|M_{1}} = -2.3V$ and $E^{0}_{M^{2+}_{1}|M_{1}} = 0.2V$ Predict which one is better for coating the surface of iron. Given: $E^{0}_{Fe^{2+}|Fe} = -0.44$V.

119. What are the types of changes in the cathode and anode in electrolytic and electrochemical cells?

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

121. How are colloidal solution of ink and graphite prepared?

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

123. How can the following conversion be effected? (i) Phenol to phenolphthalein.

124. What is Rosenmund's reduction? What is the purpose of adding BaSO4 in it?

125. Part - D

12 x 5 = 60
126. Explain refining of nickel by mond's process

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

128. Give a detailed account on allotropes of sulphur.

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

130. Mention the type of hybridisation and magnetic property of the following complexes using VB theory a) [FeF6]4- b) [Fe(CN)6]4-

131. Explain the following:
Similarities and differences between metallic and ionic crystals.

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. A zinc rod is placed in 0.095 M zinc chloride solution at 25°c. Emf of this half cell is -0.79 V. Calculate EoZn2+/Zn

135. Explain the electrical property of colloids! with a neat diagram.

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. 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