MS Chauhan Chapter 4B Hydrocarbon (Alkenes)

MS Chauhan Organic Chemistry Solutions Chapter 4B explains the concepts of an unsaturated hydrocarbon that is alkenes. Some of the main topics of the MS Chauhan Solutions Chapter 4B Hydrocarbon (Alkenes) Solutions include hydrocarbon – alkenes, its properties, preparation of alkenes from E2 mechanism, E1 mechanism, hydration, and oxidation reactions.

MS Chauhan Organic Chemistry Solutions for Chapter 4B Hydrocarbon (Alkenes) has 2 main levels with a total of 242 questions. These solutions are important for you to get a good score in the CBSE as well as the competitive exams like JEE and NEET. All these questions are solved by the expert Chemistry teacher at Instasolv. Referring to these solutions you will attain perfection in solving different kinds of questions easily.

Throughout this chapter of MS Chauhan Solutions of Organic Chemistry, the concepts are explained in a comprehensive and very simple manner. We have undergone thorough research to get accurate solutions for you. So, revising the chapter with the help of solutions provided by us will help you to perform better. The solutions for MS Chauhan Organic Chemistry are available for free and can be accessed without any hassle. Follow the solutions now!

Important Topics for MS Chauhan Organic Chemistry Solutions Chapter 4B Hydrocarbon (Alkenes)


Hydrocarbons are the organic compounds collected from elements like carbon and hydrogen only. The study of hydrocarbons provides a vision into the chemical properties of other functional groups and their preparations.

We use hydrocarbons including propane and butane for the use of our commercial fuel in the form of LPG cylinders. For many of the synthetic drugs developed, benzene is the initial material.


In organic chemistry, an alkene refers to an unsaturated hydrocarbon that consists of a carbon-carbon double bond. Unsaturated hydrocarbons comprising two or more double bonds are called as alkadienes, alkatetraenes, alkatrienes, and so on. The words alkene and olefin are often considered interchangeably.

Physical Properties of Alkenes

The physical properties of alkenes are listed below:

  • Physical State: These double-bonded combinations are colourless and odourless in nature. Though, ethene is an exclusion because it is a colourless gas but has a slightly sweet odour.
  • Solubility: The alkenes are unsolvable in water due to their nonpolar features. But they are absolutely soluble in nonpolar solvents including benzene, ligroin, etc.
  • Boiling Point: The boiling points of the compounds rise as the number of carbon atoms in the compound rises. When alkenes are related to alkanes, it is found that the boiling points of both are almost equivalent, as if the compounds are made up of a similar carbon skeleton.
  • Melting Point: The melting points of these double-bonded mixtures depend upon the location of the molecules. The melting point of alkenes is equivalent to that of alkanes.

Preparation of Hydrocarbons – Alkenes

Preparation Methods

Most of the reactions including the preparation of alkenes include the elimination process. There are 3 mechanisms recommended for the elimination reactions. All these eliminations refer to the β- eliminations.

E2 Mechanism

  • It is a single-step process.
  • They are second-order kinetics.
  • Order & reactivity 1° > 2° > 3°
  • Because of steric hindrance, they are more favoured in non-polar, aprotic solvents and less substituted alkenes created as a major product.

E1 Mechanism

  • It is a two-step process.
  • They are first-order kinetics
  • Order of reactivity: 3° > 2° > 1°
  • Because of the stability of carbonation, they are more favoured by polar, protic solvents, their rearrangement is possible, and also they give more substituted alkene as major products.


  • Acid-catalysed: It is a Markovnikov product and their rearrangement is possible.
  • Hydroboration-oxidation: It is an Anti – Markonikov product and no rearrangement is possible in these reactions.
  • Oxymercuration-Demercuration: It is a Markonikov product and no rearrangement is possible in these reactions.

Oxidation Reactions

  • These reactions take place using Baeyer’s reagent
  • They use hot KMnO4
  • They use O5O4
  • Ozonolysis
  • Addition of peroxy acid

Exercise-wise Discussion for MS Chauhan Organic Chemistry Solutions Chapter 4B Hydrocarbon (Alkenes)

Chapter 4B – Hydrocarbon (Alkenes) of MS Chauhan Organic Chemistry Solutions has 2 main levels with a total of 242 questions. The detailed description of these exercises is provided below:

Level 1: This is the first level of Organic Chemistry MS Chauhan Solutions for Chapter 4B. It contains 229 objective type questions. Practising these questions will help you clear your concepts on alkenes, its properties, and the preparation of alkenes. It is considered a very important exercise from the entrance exam point of view.

Level 2: This level of MS Chauhan Chapter 4B Solutions consists of a total of 13 questions. There are two different types of questions available at this level including very short answer type questions and short answer type questions. Practice well to make your concepts stronger.

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