Alkane MCQs with Answers
51. Gasoline is obtained from crude petroleum oil by its ……………
(a) Fractional distillation
(b) Vacuum distillation
(c) Steam distillation
(d) Pyrolysis
Ans.: d
52. Which of the following does not give alkane………
(a) Reaction of I CH 3 with Na in ether
(b) Reaction of sodium acetate with sodalime
(c) Electrolysis of concentrated sodium acetate solution
(e) Reaction of ethyl chloride with alco. KOH
Ans.: d
49. LPG is a mixture of………….
(a) C6H12+ C6H6
(b) C4H10+ C3H8
(c) C2H4 + C2H2
(d) C2H4 + CH4
Ans.: b
50. Carbon black, which is used in making printer’s ink, is obtained by decomposition of………….
(a) Acetylene
(b) Benzene
(c) Carbon tetrachloride
(d) Methane
Ans.: d
51. The addition of tetraethyl lead to petrol…………
(a) Lowers its octane number
(b) Raises its octane number
(c) May raise or lower the octane number
(d) Has no effect on octane number
Ans.: b
52. Which of the following compound has maximum boiling point……..
(a) n-hexane
(b) n-pentane
(c) 2, 2-dimethyl propane
(d) 2-methyl butane
Ans.: a
53. Knocking sound occurs in engine when fuel……….
(a) Ignites slowly
(b) Ignites rapidly
(c) Contains water
(d) Is mixed with machine oil
Ans.: b
54. Petroleum is mainly a mixture of………..
(a) Alkanes
(b) Cyclohexane
(c) Benzenoid hydrocarbons
(d) Alkenes
Ans.: a
55. Which of the following has maximum boiling point……………
(a) iso-octane
(b) n-octane
(c) 2, 2, 3, 3-tetramethyl butane
(d) n-butane
Ans.: b
56. Aqueous solution of the following compound on electrolysis gives ethane……….
(a) Acetic acid
(b) Acetamide
(c) Potassium acetate
(d) Ethyl acetate
Ans.: c
57. Which of the following does not decolourise bromine solution in carbon disulphide………..
(a) Acetylene
(b) Propene
(c) Ethane
(d) Propyne
Ans.: c
58. Anhydrous sodium acetate on heating with sodalime gives………….
(a) Acetic acid
(b) Methane
(c) Calcium acetate
(d) Ethane
Ans.: b
59. Water gas is………..
(a) CO + CO2
(b) CO + N2
(c) CO + H2
(d) CO + N2 + H2
Ans.: c
60. A sample of gasoline contains 81% iso-octane and 19% nheptane. Its octane number will be……..
(a) 19
(b) 81
(c) 100
(d) 62
Ans.: b
61. The natural petroleum contains………….
(a) Saturated hydrocarbons
(b) Cyclic saturated hydrocarbons
(c) Compounds of sulphur
(d) All of these
Ans.: d
62. The preparation of ethane by electrolysis of aqueous solution of potassium acetate is called as…….
(a) Wurtz reaction
(b) Sabatier-Senderen’s reaction
(c) Kolbe’s synthesis
(d) Grignard reaction
Ans.: c
63. As the number of carbon atoms in a chain increases the boiling point of alkanes……….
(a) Increases
(b) Decreases
(c) Remains same
(d) May increase or decrease
Ans.: a
64. In the fractional distillation of crude petroleum………..
(a) Petrol condenses at the bottom of the column
(b) The gases condense at the top of the column
(c) High boiling constituents condense at the bottom of the column
(d) High boiling constituents condense at the top of the column
Ans.: c
65. 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
Ans.: c
66. Gasoline is the name of ……………
(a) Crude oil
(b) The gaseous constituents of petroleum
(c) The mixture of uncondensed gases produced in the distillation of crude oil
(d) The mixture of the residue and gas oil obtained in the distillation of crude oil
Ans.: b
67. In the process of cracking……………
(a) Organic compounds decompose into their constituent elements
(b) Hydrocarbons decompose into carbon and hydrogen
(c) High molecular weight organic compounds decompose to give low molecular weight organic compounds
(d) Hydrocarbons yield alkyl radicals and hydrogen
Ans: c
68. Octane number has 0 value for……….
(a) iso-octane
(b) n-hexane
(c) n-heptane
(d) iso-heptane
Ans.: c
69. Dry distillation of sodium propanoate with sodalime gives …………..
(a) Propane
(b) Propene
(c) Ethane
(d) Ethene
Ans.: c
70. A mixture of propene and methane is obtained by the cracking of…………..
(a) 1-butene
(b) 2-butene
(c) n-butane
(d) Isobutane
Ans.: c
71. Which of the following fractions of petroleum refining contains kerosene ? (Boiling ranges in o C are given below)
(a) 40 – 80
(b) 80 – 200
(c) 200 – 300
(d) Above 300
Ans.: c
72. On mixing tetraethyl lead to gasoline available at petrol pumps…………..
(a) Calorific value of the fuel increases
(b) Odour diminishes
(c) Less smoke is obtained on combustion
(d) Antiknock property of fuel increases
Ans.: d
73. A liquid hydrocarbon can be converted to gaseous hydrocarbon by…………..
(a) Cracking
(b) Hydrolysis
(c) Oxidation
(d) Distillation under reduced pressure
Ans.: a
74. The tetrahedral nature of carbon was first given by………….
(a) Kekule
(b) Le Bell and Van’t Hoff
(c) Pauling
(d) Armstrong and Bayer
Ans.: b
75. Formation of alkane by the action of Zn on alkyl halide is called
(a) Frankland’s reaction
(b) Wurtz reaction
(c) Cannizzaro reaction
(d) Kolbe’s reaction
Ans.: a
76. Name the hydrocarbon that is a liquid at STP……….
(a) Ethane
(b) Propane
(c) n-butane
(d) n-pentane
Ans.: d
77. Which statement is not true concerning alkanes………..
(a) Large number alkanes are soluble in water
(b) All alkanes have a lower density than water
(c) At room temperature some alkanes are liquids, some solids and some gases
(d) All alkanes burn
Ans.: a
78. Fischer Tropsch process is used for the manufacture of…………
(a) Synthetic petrol
(b) Thermosetting plastics
(c) Ethanol
(d) Benzene
Ans.: a
79. A fuel contains 25 % n-heptane and 75 % iso-octane. Its octane number is……………
(a) 50
(b) 75
(c) 100
(d) 25
Ans.: b
80. Sodium ethoxide is a specific reagent for……………
(a) Dehydration
(b) Dehydrogenation
(c) Dehydrohalogenation
(d) Dehalogenation
Ans.: c
81. Which of the following has highest percentage of hydrogen………..
(a) CH4
(b) C2H4
(c) C6H6
(d) C2H2
Ans.: a
82. What is the molecular formula of the alkane, the 5.6 litre of which weight 11 g at STP……….
(a) C6 H14
(b) C4H10
(c) C3H8
(d) C2H6
Ans.: c
83. 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
Ans.: d
84. When sodium propionate is heated with soda lime, the main product is…………..
(a) Ethane
(b) Methane
(c) Propane
(d) Butane
Ans.: a
85. Gasoline is a mixture of alkanes with the number of carbon atoms …………….
(a) C3 + C5
(b) C5 + C6
(c) C6 + C8
(d) C7 + C9
Ans.: d
86. The final product of complete oxidation of hydrocarbons is ………..
(a) Acid
(b) Aldehyde
(c) H2O + CO2
(d) Dihydric alcohol
Ans.: c
87. Which of the following will have least hindered rotation about carbon-carbon bond…………
(a) Ethane
(b) Ethylene
(c) Acetylene
(d) Hexachloroethane
Ans.: a
88. How many types of carbon atoms are present in 2, 2, 3trimethylpentane………..
(a) One
(b) Two
(c) Three
(d) Four
Ans.: d
89. Which one gives only one monosubstitution product on chlorination………..
(a) n-pentane
(b) (b) Neopentane
(c) (c) Isopentane
(d) (d) n-butane
Ans.: b
90. 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
Ans.: d
91. Which one of the following compounds does not give addition reactions………………
(a) Aldehydes
(b) Alkanes
(c) Alkenes
(d) Alkynes
Ans. : b
92. The most important method of preparation of hydrocarbons of lower carbon number is………….
(a) Pyrolysis of higher carbon number hydrocarbons
(b) Electrolysis of salts of fatty acids
(c) Sabatier and Senderen’s reaction
(d) Direct synthesis
Ans.: a
93. The inorganic origin of petroleum is indicated by the fact that…………..
(a) Its constituents can be separated by fractional distillation
(b) Carbon and hydrocarbon can combine by absorption of solar energy to give hydrocarbons
(c) Petroleum contains traces of chlorophyll
(d) Oil fields are located with the help of seismograph
Ans.: b
94. By Wurtz reaction, a mixture of methyliodide and ethyliodide gives………….
(a) Butane
(b) Ethane
(c) Propane
(d) A mixture of the above three
Ans.: d
95. Product obtained by nitration of propane is …………….
(a) Nitropropane
(b) Nitromethane
(c) Nitroethane
(d) All of these
Ans.: d
96. Isomerism in saturated hydrocarbons is due to…………..
(a) Change in the valence of carbon
(b) Change in the ratio of elements in compounds
(c) Formation of branches in the chain of C atoms
(d) Formation of double bond
Ans.: c
97. Which of the following is not linked with methane………….
(a) Marsh gas
(b) Natural gas
(c) Producer gas
(d) Coal gas
Ans.: c
98. Which of the following has highest octane number…………..
(a) n-hexane
(b) n-heptane
(c) Iso-octane
(e) n-heptane and iso-octane mixed in ratio 50 : 50
Ans.: c
99. A mixture of ethyl iodide and n-propyl iodide is subjected to Wurtz reaction. The hydrocarbon that will not be formed is…………..
(a) n-butane
(b) n-propane
(c) n-pentane
(d) n-hexan
Ans.: b
100. Most of the hydrocarbons from petroleum are obtained by…………….
(a) Fractional distillation
(b) Fractional crystallization
(c) Vaporization
(d) Polymerization
Ans.: a
101. 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)
Ans.: d
102. In the dichlorination reaction of propane, mixture of products are obtained. How many isomers, the mixture contains…………
(a) 2
(b) 3
(c) 4
(d) 5
Ans.: c
103. Which of the following cycloalkane gives open chain compound, when reacts with bromine………..
(a) Cyclopropane
(b) Cyclopentane
(c) Cyclohexane
(d) Cyclo-octane
Ans.: a
104. Grignard reagent is not prepared in aqueous medium but prepared; in ether medium because the reagent…………..
(a) Reacts with water
(b) Is insoluble in water
(c) Is highly reactive in ether
(d) Becomes inactive in water
Ans.: a
105. A sample of petrol is a mixture of 30% n-heptane and 70% iso-octane. The sample has octane number…………
(a) 30
(b) 70
(c) 15
(d) 35
Ans.: b
106. Photochemical chlorination of alkane is initiated by a process of……………
(a) Pyrolysis
(b) Substitution
(c) Cracking
(d) Peroxidation
(e) Homolysis
Ans.: e
107. A petroleum fraction having boiling range 70-200°C and containing 6-10 carbon atoms per molecule is called………..
(a) Natural gas
(b) Gas oil
(c) Gasoline
(d) Kerosene
Ans.: c
108. Pick out the alkane which differs from the other members of the group.
(a) 2,2-dimethyl propane
(b) Pentane
(c) 2-methyl butane
(d) 2,2-dimethyl butane
Ans.: d
109. 2-Methylbutane on reacting with bromine in the presence of sunlight gives mainly……..
(a) 1-bromo-2-methylbutane
(b) 2-bromo-2-methylbutane
(c) 2-bromo-3-methylbutane
(d) 1-bromo-3-methylbutane
Ans.: b
110. Of the five isomeric hexanes, the isomer which can give two monochlorinated compounds is…………..
(a) n-hexane
(b) 2, 3-dimethylbutane
(c) 2, 2-dimethylbutane
(d) 2-methylpentane
Ans.: b
