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ALKANE

1. Which represents an alkane
A: C7H16
Solution: C7H16 (CnH2n + 2)

 

2. The decreasing order of boiling points is
A: n-Pentane > iso-Pentane > neo-Pentane

 

3. To prepare a pure sample of n-hexane using sodium metal as one reactant, the other reactant will be
A: n-propyl bromide
Solution:

 

4. In the preparation of Grignard reagent from haloalkane, the metal
A: Mg

 

5. Sodium acetate can be converted to ethane by
A: Electrolysing its aqueous solution
Solution:

 

6. Which of the following compounds is used in antiknock compositions to prevent the deposition of oxides of lead on spark plug, combustion chamber and exhaust pipe
(a) Glycerol       (b) Glycol      (c) 1, 2-dibromoethane      (d) Benzene
A: 1, 2-dibromoethane     
Solution:

As leaded gasoline burns, lead metal gets deposited in the engine which is removed by adding ethylene dibromide. The lead bromide is volatile and is carried off with the exhaust gases from the engine

 

7. Which of petroleum corresponds to kerosene oil
      (a) C15 - C18        (b) C10 - C12          (c) C5 - C9          (d) C1 - C9
A: C10 - C12 

 

8. In the reaction , the product called
A: Wurtz reaction

 

9. Iodoethane reacts with sodium in the presence of dry ether. The product is
A: Butane
Solution:

 

10. Which of the following is oxidised by KMnO4
A: Isobutane
Solution:

 

11. Which of the following has maximum stability

 

12. The most volatile compound is
A: 2, 2-dimethyl propane

 

13. In Wurtz reaction, the reagent used is
A: Na/dry ether
Solution:

 

14. Which of the following has highest octane number
(a) n-hexane       (b) n-heptane       (c) n-pentane       (d) 2, 2, 4-trimethyl pentane
A: 2, 2, 4-trimethyl pentane
Solution: iso-octane i.e. 2, 2, 4-trimethyl pentane has highest octane number.

 

15. What is freon-12
A: Refrigerant

 

16. The petrol having octane number 80 has
A: 20% normal heptane + 80% iso-octane


17. Which of the following reactions will not give propane

Solution: With calculated amount of Grignard reagent, acetyl chloride forms ketones.

 

18. The shape of methane molecule is
A: Tetrahedral
Solution:

 

19. Which of the following shows only one brominated compound
(a) Butene-2      (b) 2, 2-dimethylpropane      (c) Butyne-1      (d) Butanol-3
A: 2, 2-dimethylpropane

 

20. Kerosene is used as fuel because it is
A: More volatile

22. Which of the following statements is not true for ethane
(a) It can be chlorinated with chlorine                 (b) It can be catalytically hydrogenated
(c) When oxidised produces CO2 and H2O          (d) It is a homologue of iso-butane
A: It can be catalytically hydrogenated
Solution: Ethane is a saturated compound it can not be catalytically hydrogenated.

 

23. Petroleum refining is
A: Distillation of petroleum to get different fractions

 

24. The chemical added to leaded petrol to prevent the deposition of lead in the combustion chamber is
A: Ethylene dibromide

 

25. In the commercial gasolines, the type of hydrocarbons which are more desirable is
A: Branched hydrocarbon
Solution:
Branched hydrocarbons are more desirable because they are more volatile.

 

26. Which of the following is not formed by the reaction of Cl2 on CH4 in sunlight
(a) CHCl3    (b) CH3Cl     (c) CH3CH3    (d) CH3CH2CH3
A: CH3CH2CH3
Solution:

 

27. Which of the following has the highest boiling point
(a) Neopentane      (b) n-butane       (c) n-heptane      (d) Isobutane
A: n-heptane

 

28. Which gives CH4 when treated with water
A: Aluminium carbide
Solution:

 

29. Which of the following does not react with PCl5
(a) CH3OH     (b) CH3COOH       (c) CH3CHO      (d) C2H6
A: C2H6

 

30. Which of the following compounds is insoluble even in hot concentrated H2SO4
(a) Ethylene     (b) Benzene     (c) Hexane    (d) Aniline
A: Hexane

 

31. A reaction between methyl magnesium bromide and ethyl alcohol gives
A: Methane

Solution:

 

32. Methane and ethane both can be obtained in single step from
A: CH3I
Solution:

 

33. Paraffin wax is
A: Saturated hydrocarbon

 

34. The number of possible enantiomeric pairs that can be produced during monochlorination of 2-methylbutane is
A: 2

 

35. Petroleum consists mainly of
A: Aliphatic hydrocarbons

 

36. Petroleum ether can be used as
A: Solvent for fat, oil, varnish and rubber
Solution: Solvent for fat, oil, varnish and rubber

 

37. Which of the following are produced from coaltar
    (a) Synthetic dyes     (b) Drugs     (c) Perfumes     (d) All the three
A: All the three
Solution: Synthetic dyes, drugs, perfumes all are made from coal tar.

 

38. In alkanes, the bond angle is
A: 109.5ºC
Solution: In alkanes, hybridization is sp3. Hence bond angle is 109º.5'.

 

39. In the preparation of alkanes; a concentrated aqueous solution of sodium or potassium salts of saturated carboxylic acid are subjected to
A: Electrolysis
Solution:

 

40. Halogenation of alkanes is an example of
A: Free-radical substitution

 

41. Propionic acid is subjected to reduction with hydroiodic acid in the presence of a little P, the product formed is
A: Propane
Solution:

 

42. When ethyl iodide and propyl iodide react with Na in the presence of ether, they form
A: Three alkanes
Solution:

 

43. The alkane that yields two isomeric monobromo derivatives is
A: Propane

 

44. Kerosene is a mixture of
A: Alkanes

 

45. When petroleum is heated the vapours contain mainly
A: Petroleum ether

 

46. Iso-octane is mixed to the petrol
A: As an antiknock

 

47. Tetraethyl lead is used as
A: Petroleum additive

 

48. Cyclohexane, a hydrocarbon floats on water because
A: It is immiscible and lighter than water
Solution: Cyclohexane, is immiscible and lighter than water. Hence, floats on the surface of water.

 

49. Natural gas contains mainly
A: Methane
Solution: Methane is the main component of natural gas.

 

50. Which compound is not inflammable
A: CH4

 

51. Propane is obtained from propene, by which of the following methods
(a) Wurtz reaction            (b) Dehydrogenation
(c) Frankland reaction     (d) Catalytic hydrogenation
A: Catalytic hydrogenation

 

52. The organic compound used as antiknock agent in petroleum is
A: (C2H5)4pb

 

53. In catalytic reduction of hydrocarbons which catalyst is mostly used
A: Pt /Ni
Solution: Pt./Ni is used in catalytic reduction of hydrocarbon.

 

54. Ethylene reacts with bromine to form
A: Br - CH- CH2Br

 

55. Gasoline is obtained from crude petroleum oil by its
A: Fractional distillation
Solution: Fractional distillation is used because the difference between the boiling point of different component is less.

 

56. Which of the following does not give alkane
(a) Reaction of CH3I with Na in ether
(b) Reaction of sodium acetate with sodalime
(c) Electrolysis of concentrated sodium acetate solution
(d) Reaction of ethyl chloride with alco. KOH
A: Reaction of ethyl chloride with alco. KOH
Solution:

In presence of alc. KOH dehydrohalogenation occur and alkene is formed.
 

57. LPG is a mixture of
A: C4H10 + C3H8
Solution: Liquefied petroleum gas is a mixture of ethane, propane and butane. The main component is butane.

 

58. Carbon black, which is used in making printer's ink, is obtained by decomposition of
A: Methane

Solution:

It contains 98-99% carbon. It is used in making black ink, paints and shoe polishes.
 

59. The addition of tetraethyl lead to petrol
A: Raises its octane number
Solution: Tetraethyl lead is anti-knocking agent it increases the octane no. of the fuel.

 

60. Which of the following compound has maximum boiling point
(a) n-hexane       (b) n-pentane       (c) 2, 2-dimethyl propane    (d) 2-methyl butane
A: n-hexane       
Solution: n-hexane because it is linear therefore strong Vander Waal force

 

61. Knocking sound occurs in engine when fuel
A: Ignites rapidly
Solution: Knocking - Sudden and irregular burning of the fuel mixture causing jerks against the piston and gives rise to violent sound. This is known as knocking.

 

62. Petroleum is mainly a mixture of
A: Alkanes

 

63. Which of the following has maximum boiling point
(a) iso-octane     (b) n-octane     (c) 2, 2, 3, 3-tetramethyl butane     (d) n-butane
A: n-octane
Solution:
 Boiling point depends on molecular mass. Greater the molecular mass higher will be the boiling point.
 Boiling point also depends on the structure. If two compounds have same molecular mass then straight chain or linear compound has higher boiling point.

 

64. Aqueous solution of the following compound on electrolysis gives ethane
A: Potassium acetate
Solution:

 

65. Which of the following does not decolourise bromine solution in carbon disulphide
(a) Acetylene        (b) Propene       (c) Ethane      (d) Propyne
A: Ethane

Solution: Ethane does not decolourise bromine solution because it is a saturated compound.
 

66. Anhydrous sodium acetate on heating with sodalime gives
A: Methane
Solution:

 

67. Water gas is
A: CO + H2

 

68. A sample of gasoline contains 81% iso-octane and 19% n-heptane. Its octane number will be
A: 81
Solution: Octane number is related to the percentage of iso-octane since iso-octane is 81% hence octane number is 81%.

 

69. The natural petroleum contains
(a) Saturated hydrocarbons    (b) Cyclic saturated hydrocarbons
(c) Compounds of sulphur     (d) All of these
A: All of these

 

70. The preparation of ethane by electrolysis of aqueous solution of potassium acetate is called as
A: Kolbe's synthesis
Solution:

Solution:

 

72. As the number of carbon atoms in a chain increases the boiling point of alkanes
A: Increases
Solution: Boiling point of alkanes increases with the number of carbon atoms because surface area increases which increases the Vander Waal forces.

 

73. In the fractional distillation of crude petroleum
A: High boiling constituents condense at the bottom of the column

 

74. Which of the following is not an endothermic reaction
(a) Dehydrogenation                (b) Ethane to ethene
(c) Combustion of propane     (d) Change of chlorine molecule into chlorine atoms.
A: Combustion of propane     

Solution: The enthalpy of combustion i.e., H is always negative. It means combustion is an exothermic reaction.
 

75. Gasoline is the name of
A: The gaseous constituents of petroleum

 

76. In the process of cracking
A: High molecular weight organic compounds decompose to give low molecular weight organic compounds

 

77. Octane number has 0 value for
A: n-heptane

 

78. Dry distillation of sodium propanoate with sodalime gives
A: Ethane
Solution: 


 

79. What is the chief product obtained when n-butane is treated with bromine in the presence of light at 130ºC
A:

Solution:

2-Bromobutane is the main product because
2º carbonium ion is more stable than 1º.

 

80. A mixture of propene and methane is obtained by the cracking of
A: n-butane
Solution:

 

81. Which of the following fractions of petroleum refining contains kerosene ? (Boiling ranges in are given below)
(a) 40 - 80         (b) 80 - 200           (c) 200 - 300         (d) Above 300
A: 200 - 300 

 

82. Which of the following statements is incorrect ? The members of the homologous series of alkanes
       (a) Are all straight chain compounds
       (b) Have the general formula CnH2n+2
       (c) Have similar chemical properties
       (d) Show a regular gradation of physical properties
A: Are all straight chain compounds

 

83. On mixing tetraethyl lead to gasoline available at petrol pumps
A: Antiknock property of fuel increases
Solution: Anti-knocking properties of fuel increases.

 

84. A liquid hydrocarbon can be converted to gaseous hydrocarbon by
A: Cracking
Solution:

 

85. The tetrahedral nature of carbon was first given by
A: Le Bell and Van't Hoff

 

86. Formation of alkane by the action of Zn on alkyl halide is called
A: Frankland's reaction

 

87. Which of the following compounds will form a hydrocarbon on reaction with Grignard reagent
a) CH3CH2OH        b) CH3CHO         c) CH3COCH3          d) CH3CO2CH2
A: CH3CH2OH
Solution:

 

88. Name the hydrocarbon that is a liquid at STP
A: n-pentane

 

89. Which statement is not true concerning alkanes
A: Large number alkanes are soluble in water

 

90. Fischer Tropsch process is used for the manufacture of
A: Synthetic petrol

 

91. Which one of the following compounds cannot be prepared by Wurtz reaction
a) CH4          b) C2H6       c) C3H8       d) C4H10
A: CH4
Solution: It is not possible to prepare CH4 by wurtz reaction.

 

92. A fuel contains 25 % n-heptane and 75 % iso-octane. Its octane number is
A: 75
Solution: Octane number is the percentage by volume of iso-octane in the mixture of iso-octane and n-heptane which has the same antiknocking properties as the fuel under examination.
Given fuel (25% n-heptane +75% iso-octane) Hence, octane number = 75 (because iso octane is 75%)

 

93. Sodium ethoxide is a specific reagent for
A: Dehydrohalogenation
Solution:

 

94. Which of the following has highest percentage of hydrogen
a) CH4            b) C2H4        c) C6H6        d) C2H2
A: CH4  
Solution:

 

95. What is the molecular formula of the alkane, the 5.6 litre of which weight 11 g at STP
A: C3H8
Solution:

 

96. The reference compound `iso-octane' which is used in determining the octane number of gasoline has the structure
A: CH3 - C(CH3)2 - CH2 - CH(CH3) - CH3

 

97. Sample of 2, 3-dibromo-3-methylpentane is heated with zinc dust. The resulting product is isolated and heated with HI in the presence of phosphorus. Indicate which is the structure that represent the final organic product formed in the reaction
A:

Solution:

 

98. The order of appearance of the following with rising temperature during the refining of crude oil is
(a) Kerosene oil, gasoline, diesel           (b) Diesel, gasoline, kerosene oil
(c) Gasoline, diesel, kerosene oil           (d) Gasoline, kerosene oil, diesel
A: Gasoline, kerosene oil, diesel
Solution: Gasoline, kerosene oil, diesel

 

99. When sodium propionate is heated with soda lime, the main product is
A: Ethane
Solution:

 

100. Gasoline is a mixture of alkanes with the number of carbon atoms
A: C7 - C9
Solution: Gasoline or petrol composition C7 - C12.

 

101. The final product of complete oxidation of hydrocarbons is
A: H2O + CO2
Solution:

All hydrocarbons saturated or unsaturated on complete combustion always produce CO2 and H2O.

 

102. Which of the following will have least hindered rotation about carbon-carbon bond
(a) Ethane         (b) Ethylene           (c) Acetylene         (d) Hexachloroethane
A: Ethane
Solution: Free rotation around carbon–carbon bond takes place easily in alkanes. Now ethane and hexachloroethane both are alkanes. But in hexachloroethane bulky chlorine atom hinders the rotation. Therefore least hindered rotation takes place in ethane.

 

103. Which of the following represents the most oxidized form of hydrocarbon
(a) CO2      (b) RCHO      (c) RCOOH        (d) RCOOOH
A: CO2 
Solution:

 

104. Name the reaction

A: Cracking

Solution:

 

105. How many types of carbon atoms are present in 2, 2, 3-trimethylpentane
A: Four

 

106. Which one gives only one monosubstitution product on chlorination
(a) n-pentane         (b) Neopentane         (c) Isopentane        (d) n-butane
A: Neopentane
Solution:

Replaceable hydrogen atoms are present only on 4 primary carbon atoms. Hence, it gives only are monochloro Substituted product.

 

107. CH4 is formed when
(a) Sodium acetate is heated with sodalime       (b) Iodomethane is reduced
(c) Aluminium carbide reacts with water           (d) All of these
A: All of these
Solution:

 

108. A mixture of methane, ethylene and acetylene gases is passed through a Wolf's bottle containing ammoniacal cuprous chloride. The gas coming out is
A: A mixture of methane and ethylene
Solution: Acetylene reacts with ammonical cuprous chloride to form red ppt. of copper acetylide while methane and ethylene do not react (since they do not have acidic hydrogen) They come out from the bottle


 

109. At room temperature solid paraffin is
A: C20H42

 

110. Which one of the following compounds does not give addition reactions
(a) Aldehydes   (b) Alkanes   (c) Alkenes   (d) Alkynes   (e) Ketones   (f) All of these
A: Alkanes 
Solution: Alkanes do not give addition reactions because multiple bonds is absent.

 

111. The most important method of preparation of hydrocarbons of lower carbon number is
A: Pyrolysis of higher carbon number hydrocarbons
Solution:


 

112. The inorganic origin of petroleum is indicated by the fact that
A: Carbon and hydrocarbon can combine by absorption of solar energy to give hydrocarbons

 

113. Which of the following is a gemdihalide
(a) CH3.CHBr.CHBr.CH3      (b) CH2Br.CH2Br        (c) CHBr = CHBr      (d) CH3CHBr2
A: CH3CHBr2
Solution: In gemdihalide both the halogen atoms are present on the same carbon atom while in vicdihalide both the halagen atoms are present on adjacent carbon atoms

 

114. Which one of the following contain isopropyl group
(a) 2, 2, 3, 3-tetramethylpentane      (b) 2 - methylpentane
(c) 2, 2, 3-trimethylpentane             (d) 3, 3-dimethylpentane
A: 2 - methylpentane

Solution:

 

115. Natural gas is a mixture of
A: CH4 + C2H6 + C3H8

 

116. By Wurtz reaction, a mixture of methyliodide and ethyliodide gives
A: A mixture of the above three
Solution: All - butane, Ethane and Propane are possible in this reaction.

 

117. Product obtained by nitration of propane is
(a) Nitropropane      (b) Nitromethane     (c) Nitroethane       (d) All of these
A: All of these

 

118. Isomerism in saturated hydrocarbons is due to
A: Formation of branches in the chain of C atoms
Solution: Formation of branches in the chain of C atoms

 

119. Photochemical chlorination of alkane is initiated by a process of
A: Homolysis
Solution:  Chlorination of alkane in photochomical reaction which takes place by free radical mechanism. Free radicals are formed by homolytic bond fission or homolysis.

 

120. Which of the following is not linked with methane
       (a) Marsh gas    (b) Natural gas    (c) Producer gas  (d) Coal gas
A: Producer gas

Solution: Marsh gas, Natural gas and coal gas contains CH4 but producer gas is a mixture of Co and N2

 

121. Which of the following has highest octane number
(a) n-hexane        (b) n-heptane
(c) Iso-octane      (d) n-heptane and iso-octane mixed in ratio 50 : 50
A: Iso-octane     

 

122. A mixture of ethyl iodide and n-propyl iodide is subjected to Wurtz reaction. The hydrocarbon that will not be formed is
A: n-propane

 

123. Most of the hydrocarbons from petroleum are obtained by
A: Fractional distillation
Solution: Fractional distillation is based on the difference in the boiling point of different components.

 

124. Which is the best antiknock compound or Which one of the following substances is used as an antiknock compound
(a) Lead tetrachloride    (b) Lead acetate    (c) Zinc ethyl      (d) Tetraethyl lead (TEL)
A: Tetraethyl lead (TEL)
Solution: Tetraethyl lead (TEL) is an anti-knocking compounds when mixed with petrol tend to improve the octane no. and therefore, decreases the knocking in the cylinder of the combustion engine.

 

125. In the dichlorination reaction of propane, mixture of products are obtained. How many isomers, the mixture contains 
A: 4

 

126. Which of the following cycloalkane gives open chain compound, when reacts with bromine
(a) Cyclopropane     (b) Cyclopentane     (c) Cyclohexane     (d) Cyclo-octane
A: Cyclopropane

 

127. Grignard reagent is not prepared in aqueous medium but prepared; in ether medium because the reagent
A: Reacts with water

 

128. A sample of petrol is a mixture of 30% n-heptane and 70% iso-octane. The sample has octane number
A: 70
Solution: Petrol sample 30% n-heptane + 70% iso-octane since iso-octane is 70%. Hence, octane no. is 70.

 

129. For the reduction of ketones to hydrocarbon, the appropriate agent is
A: Zn - Hg/HCl

 

130. Heating of alkanes with fuming sulphuric acid or oleum at high temperature, which forms sulphonic acid, is called
A: Sulphonation

 

131. Propane is obtained from propene by which method ?
A: Catalyst hydrogenation
Solution:


 

132. B.P. of branched chain alkanes as compared to straight chain alkanes are
A: Lower
Solution:
As the number of branches increases, surface area decreases, due to which Vander Waal forces of attraction decreases. Hence, boiling point also decreases.

 

133. Daily use candles (paraffin wax) contain
A: Higher saturated hydrocarbon

 

134. The reaction   is an example of
A: Substitution reaction

 

135. Normal butane convert into isobutane by
A: AlCl3
Solution:

 

136. Alcoholic solution of KOH is used for
A: Dehydrohalogenation

Solution:

 

137. Aluminium carbide on reacting with water gives
A: Methane
Solution:

 

138. Maximum carbon-carbon bond distance is found in
A: Ethane
Solution: In C2H6, C- C bond length is 1.54Å.

 

139. Which of the following reaction is expected to readily give a hydrocarbon product in good yields
(a) 
(b) 
(c) 
(d) 
A: 
Solution: 

 

140. Out of the following fractions of petroleum, the one having the lowest boiling point is or Which of the following is obtained at lowest temperature by fractional distillation of petroleum
(a) Kerosene          (b) Diesel oil          (c) Gasoline         (d) Heavy oil
A: Gasoline 

 

141. The marsh gas detector used by miners works on the principle of
A: Difference in the rates of diffusion of gases

 

142. Methane can be prepared by
A: Decarboxylation
Solution: 

 

143. The most strained cycloalkane is
A: Cyclopropane
Solution:

Cyclopropane with a bond angle of 60º is very strained and hence very reactive.
 

144. Which does not react with chlorine in dark
A: CH4

 

145. Main constituent of marsh gas is

A: CH4
Solution: Marsh gas mainly consists of methane.

 

146. Which of the following method can be used for the preparation of methane
(a) Wurtz reaction                             (b) Kolbe's reaction
(c) Reduction of alkyl halide            (d) Hydrogenation of alkene
A: Reduction of alkyl halide 
Solution: 

 

147. Which hydrocarbon will be most stable
A: Butane

 

148. C-H bond length is greatest in
A:  C2H6

 

149. Which one of the following compounds does not form an ozonide
(a) Ethene           (b) Propyne          (c) Propene           (d) Propane
A: Propane

Solution: Propane is a saturated compound. Ozonide is formed only by alkenes or alkynes


150. Which type of hybridisation occurs in ethylene
A: SP2
Solution:


 

151. Silver acetylide when heated with HCl gives
A: C2H2
Solution: 

 

152. When sodium reacts with ethyl iodide, which of the following hydrocarbons is produced
A: Butane
Solution:

 

153. Solid methane is
A: Molecular solid

 

154. The shape of ethane is
A: Tetrahedra
Solution: All the C - C bond are single bonds. Hence SP3 -hybridization and tetrahedral structure.

 

155. CH3MgI will give methane with
A: (a) C2H5OH                 (b) CH3 - CH2 - NH2
Solution:

Alkyl group of Grignard’s reagent is involved in the formation of alkane.
 

156. Propane-1-ol can be prepared from propene by its reaction with
A: B2H6/NaOH,H2O2

 

157. The process in which higher hydrocarbons are broken down into lower hydrocarbons by controlled pyrolysis, is called
A: Cracking

 

158. Successive alkanes differ by
A: 

 

159. General formula of alkane is
A: CnH2n+2
Solution:

 

160. Methane and ethane both can be prepared in one step by which of the following compound
A: CH3Br
Solution: 

 

161. Photochemical chlorination of alkane is initiated by a process of
A: Homolysis
Solution: Photochemical chlorination of alkane take place by free radical mechanism which are possible by Homolysis of C – C bond

 

162. A petroleum fraction having boiling range 70-200°C and containing 6-10 carbon atoms per molecule is called
A: Gasoline

 

163. Producer gas is a mixture of
A: CO and N2
Solution: Producer gas – CO and N2

 

164. The highest boiling point is expected for
A: n - octane
Solution: Among alkanes, boiling point increase with increasing molecular weight. For isomeric alkanes straight chain alkanes have higher boiling point than the branched alkanes.

 

165. Which of the following is a good conductor of heat of electricity
(a) Diamond     (b) Graphite     (c) Anthracite     (d) Charcoal
A: Graphite
Solution: Graphite is a good conductor of heat of electricity.

 

166. Which one of the following has the minimum boiling point
(a) 1-Butene    (b) 1-Butyne    (c) n-Butane    (d) Isobutane
A: Isobutane
Solution: Among the isomeric alkanes, the normal isomer has a higher boiling point than the branched chain isomer. The greater the branching of the chain, the lower is the boiling point. The n-alkane have larger surface area in comparison to branched chain isomer (as the shape approaches that of a sphere in the branched chain isomers). Thus, intermolecular forces are weaker in branched chain isomers, there fore they have lower point in comparision to straight chain isomers.

 

167. Octane number can be changed by
(a) Isomerisation    (b) Alkylation    (c) Cyclisation    (d) All of these
A: All of these
Solution: The octane numbers of Fuel can be improved by increasing the percentage of branched chain alkanes, alkenes and aromatic hydrocarbon. Thus octane number can be changed by isomerisation (reforming), alkylation and aromatisation (cyclisation) etc.

 

168. Gasoline has composition
A: C6 - C11
Solution: The approximate composition of gasoline is C6 - C11 at boiling point 70-200°C and is used in motor fuel, dry cleaning, petrol gas etc.

 

169. The complete combustion of CH4 gives
A: CO2 + H2O
Solution:  

 

170. Which of the following has highest knocking
(a) Olefins                                   (b) Branched chain olefins
(c) Straight chain olefins           (d) Aromatic hydrocarbons
A: Straight chain olefins        
Solution: Straight chain olefins has highest knocking.  

 

171. Which one of the following compounds gives methane on treatment with water
(a) Al4C3       (b) CaC2      (c) VC      (d) SiC      (e) B4C
A: Al4C3 

Solution:

 

172. Pick out the alkane which differs from the other members of the group.
A: 2, 2-dimethyl butane
Solution: Except 2, 2 dimethyl butane rest compound contain 5 carbon i.e., pantane while 2, 2 dimethyl butane contain 6 carbon i.e., Hexane

 

173. 2-Methylbutane on reacting with bromine in the presence of sunlight gives mainly
A: 2-bromo-2-methylbutane
Solution:

 

174. Of the five isomeric hexanes, the isomer which can give two monochlorinated compounds is
A: 2, 3-dimethylbutane
Solution:

 

175. The product obtained on reaction of C2H5Cl with hydrogen over palladium carbon is
A: C2H6
Solution: 

This reaction is used for the preparation of pure alkanes.

Posted Date : 19-02-2021

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