" /> -->

#### Important Questions Part-V

12th Standard EM

Reg.No. :
•
•
•
•
•
•

Chemistry

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

Part - A

60 x 1 = 60
1. Bauxite has the composition

(a)

Al2O3

(b)

Al2O3nH2O

(c)

Fe2O3.2H2O

(d)

None of these

2. Electrochemical process is used to extract

(a)

Iron

(b)

(c)

Sodium

(d)

silver

3. Which one of the following element is present as a~ impurity in pig iron?

(a)

Phosphorus

(b)

Manganese

(c)

Carbon

(d)

Silicon

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

(a)

1

(b)

0

(c)

+2

(d)

-2

5. Metal oxide is converted into metal by the:_______ process.

(a)

Calcination

(b)

roasting

(c)

smelting

(d)

beesemerisation

6. Which of the following statements is not correct?

(a)

Beryl is a cyclic silicate

(b)

Mg2SiO4 is an orthosilicate

(c)

SiO44−i the basic structural unit of silicates

(d)

Feldspar is not aluminosilicate

7.  Column-I Column-II A Borazole 1 B(OH)3 B Boric acid 2 B3N3H6 C Quartz 3 Na2[B4O5(OH)4]8H2O D Borax 4 SiO2
(a)
 A B C D 2 1 4 3
(b)
 A B C D 1 2 4 3
(c)
 A B C D 1 2 4 3
(d)

None of these

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. Boron compounds behave as Lewis acid, because of their

(a)

ionisation property

(b)

acidic nature

(c)

covalent nature

(d)

electron deficient nature

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. 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

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. Thr hybridisation and shape of SF6 is respectively?

(a)

sp3d2,square planar

(b)

sp3d2,octahedral

(c)

sp3d see-saw

(d)

sp3d,trigonal bipyramindal

15. The incorrect statement regarding structure of ozone is______

(a)

Bond angle is less than 120°

(b)

It is linear

(c)

The two oxygen-oxygen bond length in ozone are identical

(d)

Both (b) and (c).

16. Which one of the following ions has the same number of unpaired electrons as present in V3+?

(a)

Ti3+

(b)

Fe3+

(c)

Ni2+

(d)

Cr3+

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. CrO3 is coloured due to

(a)

Low l.E

(b)

Crystal defects

(c)

Charge transfer spectra

(d)

Unpaired electrons

19. The general electronic configuration of d-block elements can be written as __________

(a)

[Noble gas]n - 1d1-10 ns1-2

(b)

[Noble gas]n - 1d-10 n1-6

(c)

[Noble gas]n - 2 d10 ns1-2

(d)

[Noble gas]n - 2 d10 ns1-6

20. Equivalent weight of KMnO4 in acidic medium is ___________

(a)

3.16

(b)

31.6

(c)

158

(d)

52.67

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

(a)

Coordination isomerism

(b)

(c)

Optical isomerism

(d)

Geometrical isomerism

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

(a)

3

(b)

4

(c)

0

(d)

15

23. 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

24. An example of ambidentate ligand is _____________

(a)

cyano

(b)

nitro

(c)

chloro

(d)

triphenylphosphine

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

(a)

Ca - EDTA

(b)

Cis - platin

(c)

Sodium thio sulphate

(d)

Nickel chloride

26. Solid CO2 is an example of

(a)

Covalent solid

(b)

metallic solid

(c)

molecular solid

(d)

ionic solid

27. 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)

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

28. The site labelled as 'X' in FCC arrangement is________

(a)

Face with 1/4 contribution

(b)

Edge with 1/4 contribution

(c)

Corner with 1/4 contribution

(d)

Tetrahedral void with 1/8 contribution

29. Iodine crystals are __________.

(a)

covalent

(b)

ionic

(c)

metallic

(d)

molecular

30. Crystals of NaCI has yellow colour due the presence of_________.

(a)

cation vaccancy

(b)

F centres

(c)

both (a) and (b)

(d)

neither (a) nor (b)

31. During the decomposition of H2O2 to give dioxygen, 48 g O2 is formed per minute at certain point of time. The rate of formation of water at this point is

(a)

0.75 mol min−1

(b)

1.5 mol min−1

(c)

2.25 mol min−1

(d)

3.0 mol min−1

32. The half life period of a radioactive element is 140 days. After 560 days , 1 g of element will be reduced to

(a)

$\left( \cfrac { 1 }{ 2 } \right) g$

(b)

$\left( \cfrac { 1 }{ 4 } \right) g$

(c)

$\left( \cfrac { 1 }{ 8 } \right) g$

(d)

$\left( \cfrac { 1 }{ 16 } \right) g$

33. Which order reaction obeys the expression ${ t }_{ \frac { 1 }{ 2 } }\alpha \frac { 1 }{ \left[ A \right] } ?$

(a)

First

(b)

Second

(c)

Third

(d)

Zero

34. For an exothermic chemical process occurring in 2 steps as
(i) A +B ⟶ X (slow) ;
(ii) X ⟶  AB (fast)
The progress of the reaction can be best described by (x- intermediate).

(a)

(b)

(c)

(d)

None of these

35. What will be the rate constant of a I order reaction if its half life is given to be 20 min?

(a)

13.86 min-1

(b)

28.86 min-1

(c)

3.47 X 10-2 min-1

(d)

None of these

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. 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

38. An example of basic buffer is

(a)

NH4OH and NH4CI

(b)

NH4OH and NaOH

(c)

NaOH and NH4Cl

(d)

NaOH and KOH

39. ${ X }_{ m }{ Y }_{ n(s) }\overset { { H }_{ 2 }O }{ \rightleftharpoons } { mX }_{ (aq) }^{ n+ }+{ nY }_{ (aq) }^{ m- }$

(a)

${ [{ X }^{ n+ }] }^{ m }{ [Y^{ m- }] }^{ n }$

(b)

${ [X }^{ n+ }][{ Y }^{ m- }]$

(c)

${ [{ X }^{ n+ }] }^{ m }/{ [Y^{ m- }] }^{ n }$

(d)

${ [X }^{ n+ }]/[{ Y }^{ m- }]$

40. According to Lowry - Bronsted theory, an acid is a ______

(a)

electron donor

(b)

electron acceptor

(c)

proton donor

(d)

prof on acceptor

41. Among the following cells
I) Leclanche cell
IV) Mercury cell
Primary cells are

(a)

I and IV

(b)

I and III

(c)

III and IV

(d)

II and III

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. Ionic conductance at infmite dilution of Al3+ and SO2-4 are 1890 ohm-1 cm2 gm equiv-1 and 1600 ohm-1 cm-2 gm equiv-1 respectively. The equivalent conductance is

(a)

143 mho cm2 gm equiv-1

(b)

850 mho cm2 gm equir-1

(c)

153 mho cm2 gm equiv-1

(d)

314 mho cm2 gm equir-1

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

(a)

Wmax = ΔH

(b)

Wmax = ΔG

(c)

Wmax = ΔE

(d)

Wmax = ΔS

45. Unit of resistivity is ___________

(a)

ohm metre

(b)

siemen

(c)

sm-1

(d)

mho

46. Fog is colloidal solution 0 of

(a)

solid in gas

(b)

gas in gas

(c)

liquid in gas

(d)

gas in liquid

47. Collodion is a 4% solution of which one of the following compounds in alcohol – ether mixture?

(a)

Nitroglycerine

(b)

Cellulose acetate

(c)

Glycoldinitrate

(d)

Nitrocellulose

48. A substance which destroys the activity of a catalyst is________

(a)

negative catalyst

(b)

catalytic poison

(c)

both (a) and (b)

(d)

promoter

49. The emulsifying agent used in O/W type is

(a)

lampblack

(b)

alcohols

(c)

gums

(d)

heavy metal salts of fatty acids

50. An example of lyophilic colloid is__________

(a)

sulphur in water

(b)

phosphorus in water

(c)

starch

(d)

all of these

51. (CH3)3-C-CH(OH) CH3 $\overset { con{ H }_{ 2 }{ SO }_{ 4 } }{ \longrightarrow }$X (major product)

(a)

(CH3)3 CCH = CH2

(b)

(CH3)2C = C (CH3)2

(c)

CH2= C(CH3)CH2-CH2- CH3

(d)

CH2= C (CH3) - CH2- CH2- CH3

52. The reaction

Can be classified as

(a)

dehydration

(b)

Williams on alcoholsynthesis

(c)

Williamson ether synthesis

(d)

dehydrogenation of alcohol

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. 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

55. On heating, peroxides are ________

(a)

stable

(b)

unstable

(c)

decomposes violently

(d)

both (b) and (c)

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. The formation of cyanohydrin from a ketone is an example of

(a)

(b)

(c)

nucleophilic substitution

(d)

electrophilic substitution

59. With respect to the reagents given below, pick out the odd one _________.

(a)

P2O3

(b)

P2O5

(c)

H2SO4

(d)

K2Cr2O7

60. ${ CH }_{ 3 }CO{ CH }_{ 3 }\overset { { conc.H }_{ 2 }{ SO }_{ 4 } }{ \longrightarrow } ?$ The product is __________.

(a)

mesitylene

(b)

mesity oxide

(c)

phorone

(d)

paraldehyde

61. Part - B

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

63. Describe a method for refining nickel

64. Name the metals that are obtained from their oxides using hydrogen as reducing agent.

65. Write the chemical reactions involved in the extraction of gold by cyanide process. Also give the role of zinc in the extraction.

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 happens to CO2 when dissolved in water?

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

70. What is inert pair effect?

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

72. Elements of group 16 show lower value of first ionization enthalpy compared to group 15, why?

73. Why hydrides of oxygen is a liquid whereas hydride of sulphur is a gas?

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

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

76. Many industrial processes use transition metal or their compounds as catalyst. Why?

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. 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. [Ti(H2O)6]3+ is coloured, while [Sc(H2O)6]3+ is colourless- explain

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

81. What is the coordination number of central metal ion in [Fe(C2O4)3]3-?

82. Classify the following as amorphous or crystalline solids. Polyurethane, Naphthalene, Benzoic acid, Teflon, Potassium nitrate, Cellophane, Polyvinyl chloride, Fiber glass, Copper.

83. NaCI has a sharp melting point but glass does not - Justify.

84. Describe the graphical representation of first order reaction.

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. For a chemical reaction, Variation in the concentration In[A] Vs time in seconds is given as

(i) What is the order of the reaction?
(ii) What is the unit of rate constant K?
(iii) Give the relationship between k and ${ t }_{ \frac { 1 }{ 2 } }$

87. If the rate of a reaction gets doubled as the temperature is increased from 27oC to 37oC. Find the activation energy of reaction?

88. Calculate the concentration of OH- in a fruit juice which contains $2\times10^{-3}$ M, H3O+ ion. Identify the nature of the solution.

89. Calculate the pH of 0.001M HCl solution

90. Define Buffer solution.

91. How is common ion effect related to the solubility of the electrolyte?

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

93. Calculate the molar conductance of 0.025M aqueous solution of calcium chloride at
25°C. The specific conductance of calcium chloride is 12.04 × 10-2 Sm-1.

94. On what does the emf of a lead storage battery depend?

95. Higher the standard reduction potential lesser is corrosion. Give reason.

96. Write a note on dialysis.

97. Which will adsorb more gas, a lump of charcoal or its powder and why?

98. Give reasons: Methanol is miscible with water while iodo-methane is not.

99. Preparation of ethers by intermolecular dehydration of alcohols in the presence of an add is not a suitable method for mixed ethers. Give reason.

100. Complete the following reaction

101. Write the structural formula of
(I) p - methyl benzaldehyde
(ii) 2 - methyl cyclohexanone

102. Part - C

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

104. What is meant by aluminotherrnitc process?

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. Account for the following:
(i) CO is used in the extraction of metals.
(ii) CO is poisonous
(iii) CO2 is used in referigeration

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

110. What is meant by lanthanoid contraction?

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. Why are solids incompressible?

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. 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. Define pH.

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

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. Give the oxidation and reduction half cell reaction taking place in the Daniel cell.

120. What are the factors which influence the adsorption of a gas on a solid?

121. Write a note on auto catalysis?

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

123. Halo alkane are easily prepared from alcohols while aryl halides cannot be prepared from phenol.- Justify.

124. Write short notes on Popoff's rule.

125. Part - D

12 x 5 = 60
126. List out the application of aluminum

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

128. How is sulphuric acid manufacture by contact process?

129. Complete the following reactions
(i) Cr2O72-
(ii) Cr2O7- + 6I-+ 14H+ ⟶
(iii)  Cr2O7- + 3S2-+ 14H+ ⟶
(iv) Cr2O7- + 3SO2+ 14H+
(v) Cr2O7- +3Sn2+ + 14H+ ⟶
(vi) K2Cr2O7 + 8H2SO4 + 3CH3CH2OH ⟶
(vii) 2MnO4- + 5(COO)2- + 6H+ ⟶
(viii) 2MnO4- + 10I+ 16H+
(ix) 2MnO4- + 5S2-+ 16H+ ⟶
(x) 2MnO4- + 5NO2- + 6H+ ⟶
(xi) 2KMnO4 + 3H2SO4 + 5CH3CH2OH ⟶
(xii) 2MnO4- + 5SO32- + 6H+

130. For the complex [NiCI4]2- write (i) the IUPAC name (ii) The hybridisation type (iii) The shape of the complex

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. State the characteristics of order of reactions. (OR) Give the characteristics of order of reactions.

133. Derive the relationship between pH and pOH.

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 electrodialysis

136. What are ethers? Write note on simple and mixed ethers with examples.

137. Compound (A) with Molecular formula C7H6O does not reduce Fehling's solution. Compound (A) reacts with acetone in the presence of NaOH to give a compound (B) which is an α, β-unsa,turated compound. Further (A) reacts with dimethyl aniline in the presence of cone, H2SO4 to give compound (C) which is a dye. Identify (A) (B) and (C). Explain the reactions.