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#### Important Questions Part-IV

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 one of the following is not feasible

(a)

$Zn(s)+C{ u }^{ 2+ }\left( aq \right) \rightarrow Cu\left( s \right) +{ Zn }^{ 2+ }(aq)$

(b)

$Cu(s)+Z{ n }^{ 2+ }(aq)\longrightarrow Zn(s)+{ Cu }^{ 2+ }(aq)$

(c)

$Cu(s)+2Ag^{ + }(aq)\longrightarrow Ag(s)+{ Cu }^{ 2+ }(aq)$

(d)

$Fe(s)+{ Cu }^{ 2+ }(aq)\longrightarrow Cu(s)+{ Fe }^{ 2+ }(aq)$

2. Flux is a substance which is used to convert

(a)

Mineral into silicate

(b)

Infusible impurities to soluble impurities

(c)

Soluble impurities to infusible impurities

(d)

All of these

3. Which metal is used for extraction of Au and Ag and also for galvanisation of iron objects?

(a)

Mg

(b)

Zn

(c)

Cr

(d)

Co

4. 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)

5. $ZnS+{ 3O }_{ 2 }\overset { \Delta }{ \longrightarrow } 2ZnO+{ 2SO }_{ 2 }\uparrow$ .The above equation is an example for________.

(a)

calcination

(b)

reduction

(c)

roasting

(d)

leaching

6. Which among the following is not a borane?

(a)

B2H6

(b)

B3H6

(c)

B4H10

(d)

none of these

7. The basic structural unit of silicates is (NEET)

(a)

$\left( SiO_{ 3 } \right) ^{ 2- }$

(b)

$\left( SiO_{ 4 } \right) ^{ 2- }$

(c)

$\left( Sio \right) ^{ - }$

(d)

$\left( SiO_{ 4 } \right) ^{ 4- }$

8. Identify the electron - deficient species

(a)

(BH3)2

(b)

(SiH3)2

(c)

PH3

(d)

(CH3)2

9. 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

10. Group 14 elements have general electronic configuration _______

(a)

ns2

(b)

ns2np4

(c)

ns2np6

(d)

ns2np2

11. XeF6 on complete hydrolysis produces

(a)

XeOF4

(b)

XeO2F2

(c)

XeO3

(d)

XeO2

12. Which of the following is strongest acid among all?

(a)

HI

(b)

HF

(c)

HBr

(d)

HCl

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. S-S bond is present in

(a)

H2S2O7.

(b)

H2SO5

(c)

H2S2O6

(d)

H2S2O6

15. Oxidation states of P in H4P2O5' H4P2O6, H4P2O7 are respectively _________

(a)

+3, +4, +5

(b)

+3, +5, +4

(c)

+5,+3,+4

(d)

+5,+4,+3

16. the catalytic behaviour of transition metals and their compounds is ascribed mainly due to

(a)

their magnetic behaviour

(b)

their unfilled d orbitals

(c)

their ability to adopt variable oxidation states

(d)

their chemical reactivity

17. The actinoid elements which show the highest oxidation state of +7 are

(a)

Np, Pu ,Am

(b)

U, Fm, Th

(c)

U, Th, Md

(d)

Es, No, Lr

18. Which of the following is coloured due to charge transfer?

(a)

MnO4-

(b)

CrO42-

(c)

Cu2O

(d)

All of these

19. The colour of K2Cr2O7 and Fe2+ ions are respectively due to

(a)

Crystal defects and charge transfer spectra

(b)

d-d transition and charge transfer spectra

(c)

Charge transfer spectra and crystal defects

(d)

Charge transfer spectra and d-d transition

20. 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)

21. Which one of the following will give a pair of enantiomorphs?

(a)

[Cr(NH3)6][Co(CN)6]

(b)

[Co(en)2Cl2]cl

(c)

[pt(NH3)4][ptcl4]

(d)

[Co(NH3)4Cl2]NO2

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

(a)

Coordination isomerism

(b)

(c)

Optical isomerism

(d)

Geometrical isomerism

23. The oxidation number of nickel in complex ion, [NiCI4]2- is

(a)

+1

(b)

-1

(c)

+2

(d)

-2

24. What is the electronic configuration of Cr in K3[Cr(C2 O4)3] 3H2O.

(a)

d3

(b)

d2

(c)

d1

(d)

d0

25. The ligand capable of coordinating in two or more ways with the central metal ion are called ___________ ligands.

(a)

didentate

(b)

tridentate

(c)

ambidentate

(d)

none of the above

26. CsCl has bcc arrangement, its unit cell edge length is 400pm, its inter atomic distance is

(a)

400pm

(b)

800pm

(c)

$\sqrt { 3 } \times 100pm$

(d)

$\left( \cfrac { \sqrt { 3 } }{ 2 } \right) \times 400pm$

27. if ‘a’ is the length of the side of the cube, the distance between the body centered atom and one corner atom in the cube will be

(a)

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

(b)

$\left( \cfrac { 4 }{ \sqrt { 3 } } \right) a$

(c)

$\left( \cfrac { \sqrt { 3 } }{ 4 } \right) a$

(d)

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

28. Which one of the following statements is not true?

(a)

The heat of vaporisation of ionic crystals are high

(b)

Ionic crystals are soluble in non-polar solvent

(c)

Ionic crystals are hard and brittle

(d)

Ionic crystals are conductors in solution state

29. The total number of elements of symmetry in a cubic crystal is________.

(a)

9

(b)

23

(c)

10

(d)

14

30. The coordination number of Zn in ZnO and Zn in ZnS are respectively___________

(a)

4 and 6

(b)

4 and 4

(c)

2 and 4

(d)

4 and 3

31. In a reversible reaction, the enthalpy change and the activation energy in the forward direction are respectively −x kJ mol-4 and kJ mol-1 Therefore , the energy of activation in the backward direction is

(a)

(y-x)kJ mol-1

(b)

(x+y)J mol-1

(c)

(x-y)KJ mol-1

(d)

(x+y)X103Jmol-1

32. The rate constant of a reaction is 5.8X10-2. The order of the reaction is

(a)

First order

(b)

zero order

(c)

Second order

(d)

Third order

33. For the following reaction, identify the order of reaction and dimension of the rate constant.
H2O2(aq) +3I-(aq) + 2H+ ⟶ 2H2O(1) + I3- ; Rate = k[H2O2] [I]-

(a)

2, L mol-1 s-1

(b)

1. s-1

(c)

$\frac { 3 }{ 2 }$L1/2 mol-1/2 s-1

(d)

None of these

34. Compound A reacts by first order kineties. At 25oC, the rate constant of the reaction is 0.60 see:'. What is the half life of A?

(a)

1.15 sec

(b)

0.4158 sec

(c)

0.093 sec

(d)

1.29 sec

35. By the order of reaction we mean _______________

(a)

the sum of powers to which the concentration terms are raised in the rate equation

(b)

the number of reactants take part in the reaction

(c)

the number of concentration terms in the velocity equation for the reaction

(d)

the least number of product molecule needed for the reaction

36. 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

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

(a)

BF3

(b)

PF3

(c)

CO

(d)

F

38. Pick the strongest conjugate base among the following

(a)

Cl-

(b)

${ NO }_{ 2 }^{ - }$

(c)

${ SO }_{ 4 }^{ 2- }$

(d)

CH3COO-

39. Pick out the incorrect statement regarding Lewis acids and bases

(a)

A Lewis acid is a electron deficient molecule

(b)

Lewis bases is one which donates an electron pair

(c)

Lewis base is a cation

(d)

Lewis acid is a electron deficient molecule and Lewis base is a cation

40. Ionic product of water increases when

(a)

Pressure decreases

(b)

(c)

(d)

temperature increases

41. Which of the following electrolytic solution has the least specific conductance

(a)

2N

(b)

0.002N

(c)

0.02N

(d)

0.2N

42. 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

43. 1 F equals to _________

(a)

96500 moles

(b)

96500 C

(c)

1.6 x 10-19 C

(d)

1.6 X 10-19 moles

44. The cathode in Leclanche cell is ______________

(a)

Zinc container

(b)

(c)

Graphite rod in contact with MnO2

(d)

HgO mixed with graphite

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. Match the following

 a V2O5 i High density polyethylene b Ziegler – Natta ii PAN c Peroxide iii NH3 d Finely divided Fe iv H2SO4
(a)
 A B C D iv i ii iii
(b)
 A B C D i ii iv iii
(c)
 A B C D ii iii iv i
(d)
 A B C D iii iv ii i
48. Which one of the following is correctly matched?

(a)

Emulsion - Mayonnaise

(b)

Foam - Cream

(c)

Solid aerosol - Fog

(d)

Solid sol - Pumice stone

49. When temperature is raised, chemisorption______

(a)

increases

(b)

decreases

(c)

first decreases and then increases

(d)

first increases and then decreases

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

(a)

Emulsificatio

(b)

Deemulsification

(c)

Coagulation

(d)

Flocculation

51. Which one of the following is the strongest acid

(a)

2 - nitrophenol

(b)

4 – chlorophenol

(c)

4– nitrophenol

(d)

3 – nitrophenol

52. The reactions

is an example of

(a)

Wurtz reaction

(b)

cyclic reaction

(c)

Williamson reaction

(d)

Kolbe reactions

53. Which among the following statement are correct with regard to alkyl halides?

(a)

Alkyl halides on heating with aq NaOH gives alcohols

(b)

10 alkyl halides proceed by SN2 mechanism

(c)

20 and 30 alkyl halides undergo substitution by SN1 mechanism

(d)

all the above

54. RX + NaOH(aq) $\overset { \triangle }{ \longrightarrow }$ ROH + NaX The above reaction proceed by _______ mechanism.

(a)

(b)

elimination

(c)

electrophilic substitution

(d)

nucleophilic substitution

55. Oxidation of ethylene glycol with HIO4 gives _______

(a)

$\overset { CHO }{ \underset { { CH }_{ 2 } }{ | } }$

(b)

$\overset { CH }{ \underset { CHO }{ | } }$

(c)

$\overset { COOH }{ \underset { COOH }{ | } }$

(d)

HCHO

56. CH3Br $\overset { KCN }{ \longrightarrow } (A)\overset { { H }_{ 2 }{ O }^{ + } }{ \longrightarrow } (B)\overset { { PCl }_{ 5 } }{ \longrightarrow }$ (C) product (c) is

(a)

acetylchloride

(b)

chloro acetic acid

(c)

$\alpha$- chlorocyano ethanoic acid

(d)

none of these

57. Phenyl methanal is reacted with concentrated NaOH to give two products X and Y. X reacts with metallic sodium to liberate hydrogen X and Y are

(a)

sodiumbenzoate and phenol

(b)

Sodium benzoate and phenyl methanol

(c)

phenyl methanol and sodium benzoate

(d)

none of these

58. Ketones when reduced in the presence of Pt forms

(a)

primary alcohols

(b)

secondary alcohol

(c)

tertiary alcohols

(d)

acids

59. Lower members of carboxylic acid family are

(a)

waxy solids

(b)

pleasant smelling liquids

(c)

foul smelling liquids

(d)

inert gases

60. The number of N-N bond in urotropine is ________.

(a)

6

(b)

4

(c)

2

(d)

0

61. Part - B

40 x 2 = 80
62. What is the role of Limestone in the extraction of Iron from its oxide Fe2O3?

63. Out of coke and CO, which is better reducing agent for the reduction of ZnO? Why?

64. Name some depressing agents

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

66. Give the uses of Borax

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

68. What are the uses of silicon tetra chloride?

69. What is crystal field splitting?

70. What is inert pair effect?

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

72. What is the reaction of Phosphorous with alkali?

73. Give the reason for bleaching action of Cl2.

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

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

76. What are coinage metals?

77. Write the outer electronic configuration of Cr atom (Z=24).

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

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

80. Define 'Ligand' Give an example of nautral legand.

81. What is Co-ordination sphere?

82. Define void.

83. Frenkel defect is not show by alkali metal halides but silver halides do. Give reason.

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. 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?

86. Mention the factors that affected the rate of a chemical reaction.

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. A lab assistant prepared a solution by adding a calculated quantity of HCl gas 250C o to get a solution with [H3O+]= 4$\times$10-5M. Is the solution neutral (or) acidic (or) basic.

89. Calculate the pH of 0.001M HCl solution

90. Give the Limitations of Arrhenius concept theory of acids and bases

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

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

96. What are the two types of catalysis?

97. Explain the kinetic property of colloids.

98. How is the following conversion effected? Ethyl alcohol ⟶ Ethylene glycol

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

100. Give nucleophilic addition reaction of acetaldehyde with NaHSO3

101. Name the reagent used in the reaction given below.
$\\ \\ \\ \underset { Sodium\quad acetate }{ { CH }_{ 3 }-\overset { \underset { || }{ O } }{ C } -ONa } +\overset { ? }{ \longrightarrow } \underset { Metahne }{ { CH }_{ 4 }+{ Na }_{ 2 }{ CO }_{ 3 } }$

102. Part - C

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

104. Explain alkali leaching in the extraction of aluminum,

105. Write a note on metallic nature of p-block elements

106. Describe the structure of carbon nanotubes.

107. How will you prepare chlorine in the laboratory?

108. Explain the characteristic properties of hydrogen halides.

109. Compare the ionization enthalpies of first series of the transition elements.

110. Why Hcl and HNO3 cannot be used for making the KMnO4 medium acidic?

111. Why tetrahedral complexes do not exhibit geometrical isomerism

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. Write a note on the assignment of atoms per unit cell in fcc.

114. Identify the order for the following reactions
(i) Rusting of Iron
(iii) $2A+3B\longrightarrow products$;rate k[A]1/2[B]2

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

117. What do you mean by buffer action?

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

119. Write the reactions taking place in anode and cathode of a mercury button cell. Give the over all redox reaction of the cell with the emf generation

120. What is the difference between a sol and a gel?

121. Explain the advantages of using nano catalyst.

122. Explain Kolbe’s reaction

123. What are the oxidation products of glycerol?

124. Write a note on
(i) Perkin's reaction, and
(ii) Knoevenagal reaction.

125. Part - D

12 x 5 = 60
126. How can you separate alumina from silica in a bauxite ore

127. Distinguish between diamond and graphite.

128. Explain the oxidising and reducing property of SO2·

129. Write a note on the ionization enthalpy of transition elements.

130. What is meant by stability of a co-ordination compound in solution? State the factors which govern stability of complexes.

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. The conversion of molecules x to y follows second order kinetics. Its concentration of x is increased to three times how will it affect the rate of formation of y?
For the reaction x ➝ y as it follows second order kinetics wherefore the rate of formation of y?

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

134. Derive a relationship between dissociation constant Ka and molar conductivity ${ \Lambda }_{ m }$

135. Write a note on Freundlich adsorption isotherm.

136. How would you distinguish between (i) methyl alcohol and ethyl alcohol (ii) benzyl alcohol and phenol, (iii) ethyl alcohol and benzyl alcohol?

137. Illustrate the reducing property of acetaldehyde with examples