NCERT Solutions for Class 11 Chemistry Chapter 9 Hydrocarbons – Free PDF

In the Hydrocarbons Class 11th NCERT solutions, students must focus on understanding the different types of hydrocarbons, isomerism, reactions, aromatic hydrocarbons, general methods of preparation, the petroleum refining, and environmental impact. Here are the topics covered in this chapter:

Class 11 Chemistry Chapter 9 Hydrocarbons Weightage in NEET and JEE Mains

Important Reactions in Class 11 Chemistry Hydrocarbons

• Important Reactions of Alkanes

• • Halogenation; Free Radical Substitution (In the presence of sunlight)
  • $$CH_4 + Cl_2 → CH_3Cl + HCl$$
  • Wurtz Reaction; Preparation of Alkanes (Dry ether)
  • $$2R-X + 2Na → R-R + 2NaX$$
  • 1.3 Decarboxylation Reaction; (Soda-lime formation)
  • $$RCOONa + NaOH → RH + Na_2CO_3$$

• Important Reactions of Alkenes

  • Hydrogenation; Addition of H₂ (Ni, Pt, or Pd catalyst)
  • $$CH_2=CH_2 + H_2 → CH_3-CH_3$$
  • Addition of Halogens; (Brown color of Br₂ disappears)
  • $$CH_2=CH_2 + Br_2 → CH_2Br-CH_2Br$$
  • Addition of HX; H⁺ adds to carbon with more H’s (Markovnikov’s Rule)
  • $$CH_3-CH=CH_2 + HBr → CH_3-CHBr-CH_3$$
  • Anti-Markovnikov’s Rule (Peroxide Effect)
  • $$CH_3-CH=CH_2 + HBr \xrightarrow{Peroxide} CH_3-CH₂-CH₂Br$$
  • Oxidation; Cold alkaline KMnO₄, purple color disappears (Baeyer’s Test)
  • $$CH_2=CH_2 + [O] → CH_2(OH)-CH_2(OH)$$

• Important Reactions of Alkynes

  • Hydrogenation; First alkene forms, then alkane
  • $$CH≡CH + H_2 → CH_2=CH_2 → CH_3-CH_3$$
  • Addition of Halogens
  • $$CH≡CH + Br_2 → CHBr=CHBr → CHBr₂-CHBr₂$$
  • Oxidation
  • $$CH≡CH + KMnO_4 → CO_2 + H_2O$$

• Important Reactions of Aromatic Hydrocarbons (Benzene)
  • Halogenation; (AlCl₃ Catalyst)
  • $$C_6H_6 + Cl_2 → C_6H_5Cl + HCl$$
  • Nitration; (H₂SO₄ Catalyst)
  • $$C_6H_6 + HNO_3 → C_6H_5NO_2 + H_2O$$
  • Friedel-Crafts Alkylation; (AlCl₃ Catalyst)
  • $$C_6H_6 + RCl → C_6H_5R + HCl$$
  • Friedel-Crafts Acylation; (AlCl₃ Catalyst)
  • $$C_6H_6 + RCOCl → C_6H_5COR + HCl$$

As per the CBSE 2025 syllabus, no topic has been added or deleted from this chapter.

The link to the free Hydrocarbons NCERT PDF is given below. It provides a reliable study material for Class 11 exams, CBSE Board, and entrance tests like NEET and JEE Mains. The study material is ideal for various exam preparations.
Class 11 Chapter 9 Hydrocarbon NCERT Solution PDF: Free Download PDF

For last-minute preparation, students can get the quick revision notes of Class 11 Physics, Chemistry, and Maths here.

Students can check below the list of all the topics that are covered in the Hydrocarbon chapter of NCERT class 11 Chemistry.

1. Classification
2. Alkanes

• Nomenclature and Isomerism
• Preparation
• Properties
• Conformations

3. Alkenes

• Structure of Double Bond
• Nomenclature
• Isomerism
• Preparation
• Properties

4. Alkynes

• Nomenclature and Isomerism
• Structure of Triple Bond
• Preparation
• Properties

5. Aromatic Hydrocarbon

• Nomenclature and Isomerism
• Structure of Benzene
• Aromaticity
• Preparation of Benzene
• Properties
• Directive Influence of a Functional Group in Monosubstituted Benzene

6. Carcinogenicity and Toxicity

The Hydrocarbons class 11 NCERT solutions are provided below. Students can solve the question with answers for exam preparation.

13.1. How do you account for the formation of ethane during chlorination of methane?

Answer: Chlorination of methane is a free radical reaction which occurs by the following mechanism involving initiation, propagation and termination steps: From the above mechanism, it is evident that during the propagation step, CH 3 free radicals are produced, which may undergo three reactions, i.e., (i), (ii) and (iii). In the chain termination step, the two CH 3 free radicals combine to form ethane (CH 3—CH 3) molecule.

13.2. Write IUPAC names of the following compounds:

Answer: (a) 2-Methykbuut-2-ene (b) Pent-1-ene-3-yne (c) But-1,3-diene (d) 4-Phenylbut-1-ene (e) 2-Methyl phenol (f) 5-(2-Methylpropyl)decane (g) 4-Ethyldeca-1,5,8-triene

13.3. For the following compounds, write structural formulas and IUPAC names for all possible isomers having the number of double or triple bond as indicated: (a) C4H8 (one double bond) (b) C5H8 (one triple bond)

Answer: (a) Isomers of C4H8 having one double bond are: (b) Isomers of C 5H 8 having one triple bond are:

13.4. Write IUPAC names of the products obtained by the ozonolysis of the following compounds: (i) Pent-2-ene (ii) 3, 4-Dimethylhept-3-ene (iii) 2-Ethylbut-l-ene (iv) 1-Phenylbut-l-ene.

Answer: