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#### Important Questions Part-VIII

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. Bauxite has the composition

(a)

Al2O3

(b)

Al2O3nH2O

(c)

Fe2O3.2H2O

(d)

None of these

2. Extraction of gold and silver involves leaching with cyanide ion. silver is later recovered by (NEET-2017)

(a)

Distillation

(b)

Zone refining

(c)

Displacement with zinc

(d)

liquation

3. The process of heating of copper pyrites to remove sulphur is called

(a)

froth flotation

(b)

roasting

(c)

calcination

(d)

smelling

4. Ignition mixture used in aluminothermite process is

(a)

Cr + AI2O3

(b)

Mg + BaO2

(c)

AI + Cr2O3

(d)

Ba+MgO

5. In acid leaching process. the insoluble sulphide is converted into soluble sulphate and elemental_________

(a)

carbon

(b)

(c)

sulphur

(d)

zinc

6. In diborane, the number of electrons that accounts for banana bonds is

(a)

six

(b)

two

(c)

four

(d)

three

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. Select the incorrect statement regarding B2H6.

(a)

It contains B-B ionic bond

(b)

Each boron is Sp3 hybridised

(c)

It has two types of hydrogen bonds

(d)

it is used as a reducing agent

9. 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

10. On moving down the group 13, density ______

(a)

decreases

(b)

increases

(c)

First decreases then increases

(d)

remains same

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. The correct order of the thermal stability of hydrogen halide is

(a)

HI > HBr > HCl > HF

(b)

HF > HCl > HBr > HI

(c)

HCl > HF > HBr > HI

(d)

HI > HCl > HF > HBr

13. Which of the following halides of group 15 is not hydrolysed?

(a)

NF3

(b)

PF3

(c)

NI3

(d)

Both (a) and (b)

14. When Copper is heated with cone HNO3 it produces

(a)

Cu (NO3)2 and N20

(b)

Cu (NO3)2 and NO2

(c)

Cu (NO3)2 and NO

(d)

Cu (NO3)2 NO and N2O

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. Which of the following statements is not true?

(a)

on passing H2S, through acidified K2Cr2O7 solution, a milky colour is observed

(b)

Na2Cr2O7 is preferred over K2Cr2O7 in volumetric analysis

(c)

K2Cr2O7 solution in acidic medium is orange in colour

(d)

K2Cr2O7 solution becomes yellow on increasing the PH beyond 7

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. What are the species X and Y in the following?

(a)

CrO3, CrO3, Cr2O3

(b)

CrO3, Cr2O3

(c)

CrO4-2, Cr2O72-

(d)

H2CrO4, H2Cr2O7

19. The correct statement is,

(a)

Cu2Cl2 and Ag2S are coloured

(b)

Upon strong heating paramagnetic gases are evolved by NaNO3 and AgNO3

(c)

Green vitriol and blue vitriol are isomorphus

(d)

KMnO4 and K2Cr2O7 are coloured due to

20. Equivalent weight of KMnO4 in acidic medium is ___________

(a)

3.16

(b)

31.6

(c)

158

(d)

52.67

21. The sum of primary valance and secondary valance of the metal M in the complex [M(en)2(Ox)]Cl isL

(a)

3

(b)

6

(c)

-3

(d)

9

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. [FeF6]4- is paramagnetic because

(a)

F- is a weaker ligand

(b)

F- is a strong ligand

(c)

F- is a flexidentate ligand

(d)

F- is a chelating ligand

24. Which of the following is not true about secondary valency?

(a)

It corresponds to the co-ordination number of metal

(b)

It is satisfied by negative ions or neutral molecule

(c)

They are non directional in nature

(d)

both (a) and (b)

25. The ionisation isomer of [Cr(H2O)4CI(NO2)]Cl is ____________

(a)

[Cr(H2O)4Cl2(NO)2]

(b)

[Cr(H2O)4Cl2]NO2

(c)

[Cr(H2O)4Cl(oNo)]

(d)

both (a) and (b)

26. Solid CO2 is an example of

(a)

Covalent solid

(b)

metallic solid

(c)

molecular solid

(d)

ionic solid

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. In a face-centered cubic lattice, a unit cell is shared equally by how many unit cells?

(a)

8

(b)

4

(c)

2

(d)

6

29. In the Bragg's equation for diffraction of X-rays, 'n' represents

(a)

The number of moles

(b)

(c)

A quantum number

(d)

Order of reflection

30. Frankel defect is also known as __________.

(a)

stoichiometric defect

(b)

dislocation defect

(c)

both (a) & (b)

(d)

non-stoichiometric defect

31. For a first order reaction, the rate constant is 6.909 min-1.the time taken for 75% conversion in minutes is

(a)

$\left( \cfrac { 3 }{ 2 } \right) { log }^{ 2 }$

(b)

$\left( \cfrac { 2 }{ 3 } \right) log2$

(c)

$\left( \cfrac { 3 }{ 2 } \right) log\left( \cfrac { 3 }{ 4 } \right)$

(d)

$\left( \cfrac { 2 }{ 3 } \right) log\left( \cfrac { 4 }{ 3 } \right)$

32. If the initial concentration of the reactant is doubled, the time for half reaction is also doubled. Then the order of the reaction is

(a)

Zero

(b)

one

(c)

Fraction

(d)

none

33. 2N2O5 ⟶ NO2 + O2$\frac { d\left[ { N }_{ 2 }{ O }_{ 5 } \right] }{ dt }$ = k1[N2O5], $\frac { d\left[ { NO }_{ 2 } \right] }{ dt }$k2[N2O5] and $\frac { d{ O }_{ 2 } }{ dt }$ = k 3[N2O5], the relation between k1, k2 and k3 is

(a)

2k1 = 4k2 = k3

(b)

k1 = k= k3

(c)

2k1 = k2 = 4k3

(d)

2k1 = k2 = k3

34. A+B $\longrightarrow$ C; ∆H = 60 kJ mol-1 Eaf = 150 kJ. What is the activation energy of the backward reaction?

(a)

210 kJ

(b)

105 kJ

(c)

90 kJ

(d)

145 kJ

35. Which of the following statement is not correct?

(a)

Molecularity of a reaction cannot be fractional

(b)

Molecularity of a reaction cannot be more than three

(c)

Molecularity of a reaction can be zero

(d)

Molecularity is assigned for each elementary step of mechanism.

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. Equal volumes of three acid solutions of pH 1,2 and 3 are mixed in a vessel. What will be the H+ ion concentration in the mixture?

(a)

3.7 ×10-2

(b)

10-6

(c)

0.111

(d)

none of these

38. Henderson equation for a weak acid and its salt is

(a)

pH= pKb+log (Salt) / (Acid)

(b)

pH = pKa + log (Salt) / (Acid)

(c)

pH = pKa +log (Salt) / (Base)

(d)

pH = pKa + log (Acid) / (Salt)

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. A drop of hydrochloric acid is added to pure water, its pH _____

(a)

increases

(b)

decreases

(c)

increases and then decreases

(d)

resist the change in pH and so remains unaltered

41. The number of electrons that have a total charge of 9650 coulombs is

(a)

6.22 ×1023

(b)

6.022 ×1024

(c)

6.022 ×1022

(d)

6.022 ×10−34

42.  Electrolyte KCl KNO3 HCl NaOAC NaCl Λ- (Scm2 mol-1) 149.9 145.0 426.2 91.0 126.5

Calculate ΛoHoAC using appropriate molar conductances of the electrolytes listed above at infinite dilution in water at 25oC.

(a)

517.2

(b)

552.7

(c)

390.7

(d)

217.5

43. Ohm's law is mathematically expressed as

(a)

I = $\frac{V}{R}$

(b)

I = $\frac{R}{V}$

(c)

V = $\frac{I}{R}$

(d)

R = $\frac{I}{V}$

44. 1 F equals to _________

(a)

96500 moles

(b)

96500 C

(c)

1.6 x 10-19 C

(d)

1.6 X 10-19 moles

45. SHE is ___________

(a)

Standard Helium Electorde

(b)

Standard Hydrogen Electrode

(c)

Standard Mercury Electrode

(d)

none of these

46. Hair cream is

(a)

gel

(b)

emulsion

(c)

solid sol

(d)

sol.

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 of the following interface cannot be obtained?

(a)

solid - solid

(b)

solid - liquid

(c)

gas - gas

(d)

liquid -Iiquid

49. The multilayer adsorption of gases on solids take place in

(a)

(b)

chemisorption

(c)

sols

(d)

active centres

50. An example of positively charged colloid is___________

(a)

clay

(b)

starch

(c)

Ag

(d)

haemoglobi

51. An alcohol (x) gives blue colour in victormayer’s test and 3.7g of X when treated with metallic sodium liberates 560 mL of hydrogen at 273 K and 1 atm pressure what will be the possible structure of X?

(a)

CH3 CH (OH) CH2CH3

(b)

CH3 – CH (OH) – CH3

(c)

CH3 – C (OH) – (CH3)2

(d)

CH3- CH2 –CH (OH) – CH2 – CH3

52. Isoprophylbenzene on air oxidation in the presence of dilute acid gives

(a)

C6H5COOH

(b)

C6H5COCH3

(c)

C6H5COC6H5

(d)

C6H5- OH

53. Lucas test is used to distinguish 10, 20 and 30

(a)

amines

(b)

nitro compound

(c)

alcohols

(d)

all the above

54. In swern method of oxidation of alcohols to aldhedye/ ketones _______ is used as an oxidising agent.

(a)

dimethyl sulfoxide

(b)

pyridimium chloro chromate

(c)

CrO3 in anhydrousmedium

(d)

Na2Cr2O7 |H+

55. The number of primary alcoholic groups in ethylene glycol is _________

(a)

0

(b)

1

(c)

2

(d)

3

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. In which of the following reactions new carbon – carbon bond is not formed?

(a)

Aldol condensation

(b)

Friedel craft reaction

(c)

Kolbe’s reaction

(d)

Wolf kishner reduction

58. Which of the following acids do not exhibit optical isomerism?

(a)

lactic acid

(b)

tartaric acid

(c)

maleic acid

(d)

both (a) and (b)

59. From which of the following, tertiary butyl alcohol is obtained by the action of methyl magnesium iodide?

(a)

HCHO

(b)

CH3CHO

(c)

CH3COCH3

(d)

CO2

60. On Kolbe's electrolysis, formic acid gives

(a)

H2

(b)

methane

(c)

ethane

(d)

none

61. Part - B

40 x 2 = 80
62. What are the various steps involved in extraction of pure metals from their ores?

63. Which type of ores can be concentrated by froth floatation method? Give two examples for such ores.

64. Write the two similarities between calcination and roasting.

65. Define metallurgy.

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 is tetraethoxy silane? How is it obtained?

69. Name the two important ores of Boron.

70. What are interhalogen compounds? Give examples.

71. What is the hybridisation of iodine in IF7? Give its structure?

72. How is ammonia prepared in the lab?

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

74. What are inner transition elements?

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

76. Give the general electronic configuration of actinoides?

77. What is Zeigler - Natta catalyst?

78. Write the formula for the following coordination compounds.
a) potassiumhexacyanidoferrate(II)
b) petacarbonyliron(0)
c) pentaamminenitrito −k−N-cobalt(III)ion
d) hexaamminecobalt(III)sulphate
e) sodiumtetrafluoridodihydroxidochromate(III)

79. Give an example of coordination compound used in medicine and two examples of biologically important coordination compounds

80. What is Co-ordination entity?

81. What is Co-ordination sphere?

82. What are primitive unit cells?

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. 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. Why is instantaneous rate preferred over average rate?

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

89. 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.

90. When temperature is increased, will ionic product of water increase or decrease? Give reason to justify your answer.

91. Why is aqueous solution of FeCl3 acidic?

92. State Faraday’s Laws of electrolysis

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 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. Give examples of primary cells.

96. What are the two types of emulsion?

97. A solid catalyst is more effective in its finely divided form - Justify.

98. Complete the following reaction giving names of products.

99. How can isopropyl alcohols be converted to t-butyl alcohol?

100. Mention the industrial use of formaldehyde.

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. Explain how the metal oxide is converted into metal using carbon as a reducing agent.

105. Give one example for each of the following
(i) icosogens
(ii) tetragen
(iii) prictogen
(iv) chalcogen

106. Find out the oxidation state of carbon in each of the following:
(i) CaC2
(ii) H2CO3
(iii) HCN
(iv) CO

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

108. Explain the structure of ammonia

109. What are interstitial compounds?

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

111. Give an example for complex of the type [Ma2b2c2] where a, b, c are monodentate ligands and give the possible isomers.

112. What is stability constant?

113. Classify the following solids in different categories based on the nature of intermolecular force operating in them: Potassium sulphate, tin, benzene, urea, ammonia, water, zinc sulphide, graphite, rubidium, argon, silicon carbide.

114. Give the characteristics of first order reaction.

115. Show that in case of first order reaction, the time required for 99.9% completion is nearly ten times the time required for half completion of the reaction.

116. Derive an expression for the hydrolysis constant and degree of hydrolysis of salt of strong acid and weak base

117. Define buffer Index

118. Two metals M1 and M2 have reduction potential values of -xV and +yV respectively. Which will liberate H2 and H2SO4.

119. Corrosion of aluminum takes place at a much slower rate than iron. Give reason

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

121. Why does physisorption decrease with increase of temperature?

122. How is phenol prepared form
i) chloro benzene
ii) isoprophy benzene

123. Give the IUPAC names of each of the following and classify them as 1°, 2° and 3°
(a) CH3(CH2)3CHOHCH(CH3)2
(b) (CH3)3C-CH2OH
(c) $({ CH }_{ 3 })_{ 2 }\underset { \overset { | }{ { C }_{ 6 }{ H }_{ 5 } } }{ C } -OH$
(d) $BrCH_{ 2 }-\underset { \overset { | }{ OH } }{ { CH }_{ 2 } } -CH-C({ CH }_{ 3 })_{ 3 }$
(e) CH2=CH-CHOHCH
(f) PhCH2OH
(g) HOCH2CH2CH2CH2C6H5
(h) (C2H5)3COH

124. Predict the product when calcium ethanoate '" and calcicum methanoate are dry distilled. Explain the reaction.

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

128. Why is dioxygen a gas but sulphur a solid?

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

130. What are the salient feature of crystal field theory?

131. What are molecular solids? Explain the types of molecular solids.

132. For the reaction 2A + B ⟶ A2B. The rate = k [A] [B]2 with k = 2.0 X 10-6 mol? L2 S-1. Calculate the initial rate of the reaction, when [A] = 0.1 mol L-1, [B] = 0.2 mol L-1. Calculate the rate of reaction after [A] is reduced to 0.06 mol L-1

133. Derive Henderson - Hasselbalch equation

134. To one molar solution of a trivalent metal salt, electrolysis was carried out and 0.667 M was the concentration remaining after electrolysis. Calculate the quantity of electricity passed.

135. Write the characteristics of catalysts.

136. Explain the mechanism involved in the intermolecular dehydration of alcohols to give ethers.

137. Give two tests for aldehydes.