This set of Class 11 Chemistry Chapter 13 Multiple Choice Questions & Answers (MCQs) focuses on “Hydrocarbons”. These MCQs are created based on the latest CBSE syllabus and the NCERT curriculum, offering valuable assistance for exam preparation.
1. Alkanes are also known as __________
Explanation: Alkanes are saturated aliphatic open chain hydrocarbons with carbon-carbon single bonds. They are inert under normal conditions they do not react with acids, bases and other reagents. They were earlier known as paraffin, in Latin Param = little and affine means affinity.
2. Is of hydrogenation is __________ on steric crowding.
a) may be related to
d) not related to
Explanation: Ease of hydrogenation depends on the steric crowding across multiple Bond, more the steric crowding, the less is reactivity towards hydrogenation. This concept is used in one of the methods of preparation of alkanes from the hydrogenation of alkenes and alkynes.
3. How many carbons are there in the product of a decarboxylation reaction when compared with the reactant?
a) two carbons more
b) one carbon more
c) one carbon less
d) an equal number of carbons
Explanation: Decarboxylation of sodium or potassium salt of fatty acids is decarboxylation reaction. This reaction is used for descending of series as the alkane obtained has one carbon less than the parent compound. Here quicklime is used as it is more hygroscopic than sodium hydroxide and keeps Sodium Hydroxide in a dry state.
4. Which of the following reaction is used to increase the length of the carbon chain?
a) Wolff Kishnn’s reaction
b) Clemmensen reduction
c) Kolbe’s electrolysis
d) Wurtz reaction
Explanation: Wurtz reaction is used to increase the length of the carbon chain, Kolbe’s electrolysis is used when alkanes require even number of carbon atoms while clemmensen reduction and wolff-kishner are used for removing water molecule.
5. Corey-House synthesis is used for alkanes having __________ number of carbon atoms.
Explanation: Corey-House synthesis is one of the methods of preparation of alkanes and this method can be used to prepare alkanes having an odd number of carbon atoms. As 6, 2, and 4 are even numbers only the compound with three carbon atoms can be prepared.
6. Alkynes are __________ in nature and first four members are __________ gases.
a) polar, white
b) nonpolar, colourless
c) polar, colourless
d) nonpolar, white
Explanation: Alkanes being nonpolar in nature, soluble in nonpolar solvents but insoluble and polar solvent such as water. The first four members of alkanes are colourless gases, the next 13 members are colourless liquids and next higher members are colourless solids, this can be explained on the basis of the magnitude of attraction forces.
7. Which of the following is not a process of halogenation of alkanes?
Explanation: Chlorination, bromination and iodination are the processes of halogenation of alkanes. Mechanism of halogenation of alkanes is free radical in nature that is the attacking reagent is a halogen-free radical, therefore it is a chain reaction.
8. In the combustion reaction of alkanes if Ethane is used how many moles of oxygen are required?
Explanation: The combustion reaction of alkanes has a standard reaction that is CnH2n+2 + (3n/2 + 1/2)O2 → nCO2 + (n + 1)H2O. In the case of combustion of ethane, n = 2. That means the number of moles of oxygen required is 3(2)/2 + 1/2 = 3.5
9. Methane cannot be prepared by the reduction of alkenes or alkynes.
Explanation: Methane cannot be prepared by reduction of alkenes or alkynes because alkanes or alkynes require a minimum of two carbon atoms in order to form, but Methane has only a single carbon in it Methane cannot be prepared by Kolbe’s electrolysis and woods reaction also.
10. Which of the following is true regarding the boiling point?
a) cannot say
b) n-Octane is greater than isooctane
c) n-Octane is less than isooctane
d) n-Octane is equal to isooctane
Explanation: The boiling point of alkanes decreases on branching and boiling point is directly proportional to the van der walls forces and the van der wall forces are directly proportional to the molecular mass as well as surface area. So we can say that the boiling point of n-Octane is greater than that of isooctane.
More MCQs on Class 11 Chemistry Chapter 13:
- Class 11 Chemistry Chapter 13 – Hydrocarbons MCQ (Set 2)
- Class 11 Chemistry Chapter 13 – Hydrocarbons MCQ (Set 3)
- Class 11 Chemistry Chapter 13 – Hydrocarbons MCQ (Set 4)
Chapter Wise MCQs for Class 11 Chemistry
- Class 11 Chemistry Chapter 1 – Some Basic Concepts of Chemistry MCQ
- Class 11 Chemistry Chapter 2 – Structure of Atom MCQ
- Class 11 Chemistry Chapter 3 – Classification of Elements and Periodicity in Properties MCQ
- Class 11 Chemistry Chapter 4 – Chemical Bonding and Molecular Structure MCQ
- Class 11 Chemistry Chapter 5 – States of Matter MCQ
- Class 11 Chemistry Chapter 6 – Thermodynamics MCQ
- Class 11 Chemistry Chapter 7 – Equilibrium MCQ
- Class 11 Chemistry Chapter 8 – Redox Reactions MCQ
- Class 11 Chemistry Chapter 9 – Hydrogen MCQ
- Class 11 Chemistry Chapter 10 – The s-Block Elements MCQ
- Class 11 Chemistry Chapter 11 – The p-Block Elements MCQ
- Class 11 Chemistry Chapter 12 – Organic Chemistry Basic Principles and Techniques MCQ
- Class 11 Chemistry Chapter 13 – Hydrocarbons MCQ
- Class 11 Chemistry Chapter 14 – Environmental Chemistry MCQ
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