By the end of this chapter you'll be able to…

  • 1Describe reactions of alkanes, alkenes and alkynes
  • 2Explain aromaticity and substitution in benzene
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Why this chapter matters
Hydrocarbons is an important chapter in Class 11 Chemistry (Samacheer Kalvi). It covers alkanes, alkenes, alkynes and aromatic compounds — concepts that are tested in the TN HSC Public Exam and build the foundation for higher-level studies.

Before you start — revise these

A 5-minute refresher here will save you 30 minutes of confusion below.

Hydrocarbons — Class 11 Chemistry (Samacheer Kalvi)

TN State Board (Samacheer Kalvi) Class 11 Chemistry, Chapter 13. Alkanes, alkenes, alkynes and aromatic compounds.


1. About this chapter

This chapter covers Hydrocarbons as part of the Class 11 Samacheer Kalvi Chemistry curriculum. It deals with alkanes, alkenes, alkynes and aromatic compounds and builds conceptual understanding essential for the TN HSC Public Exam.

By the end of this chapter, students will be able to:

  • Describe reactions of alkanes, alkenes and alkynes
  • Explain aromaticity and substitution in benzene

2. Key concepts

  • Concept 1: Describe reactions of alkanes, alkenes and alkynes.
  • Concept 2: Explain aromaticity and substitution in benzene.

3. Important terms and formulas

Term / FormulaDescription
Describe reactions of alkanes,…Describe reactions of alkanes, alkenes and alkynes
Explain aromaticity and substitution…Explain aromaticity and substitution in benzene

4. Worked examples

Example 1. Applying a key concept from this chapter.

Solution: Identify the relevant principle → apply the formula or rule → state the answer with correct units.

Example 2. A typical exam-style question on hydrocarbons.

Solution: Break the problem into steps, use the appropriate formula and verify the answer.

5. Common mistakes

  • Mistake: Skipping units or forgetting to state them. Fix: Always write units alongside every quantity and answer.
  • Mistake: Confusing similar terms or concepts in this chapter. Fix: Make a comparison table of the terms during revision.

6. Practice (exam-style)

  1. Define the main term or principle covered in Chapter 13.
  2. Give two real-life examples related to hydrocarbons.
  3. Solve a short numerical or descriptive question from this chapter.
  4. State one important formula and explain each symbol.

7. Answer key (hints)

  1. Refer to section 2 (Key concepts) above for the definition.
  2. Examples should be drawn from daily experience and local context.
  3. Apply the formula from section 3, show all steps clearly.
  4. Formula with units — refer to the textbook glossary for symbol meanings.

8. Quick revision

  • Class 11 Chemistry — Chapter 13: Hydrocarbons.
  • Core idea: Alkanes, alkenes, alkynes and aromatic compounds.
  • Key outcomes: Describe reactions of alkanes, alkenes and alkynes; Explain aromaticity and substitution in benzene.
  • Always revise diagrams / tables from the Samacheer Kalvi textbook before the exam.

Key formulas & results

Everything you need to memorise, in one card. Screenshot this for revision.

Key concept from Hydrocarbons
Refer to Samacheer Kalvi textbook
Chapter 13 — Alkanes, alkenes, alkynes and aromatic compounds.
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Common mistakes & fixes

These are the exact errors that cost students marks in board exams. Read them once, save yourself the trouble.

WATCH OUT
Skipping units in numerical answers
Always state units alongside every numerical answer for full marks.
WATCH OUT
Confusing similar concepts within the chapter
Create a side-by-side comparison table during revision.

Practice problems

Try each one yourself before tapping "Show solution". Active recall > rereading.

Q1EASY· Concept
Define the key term in Chapter 13: Hydrocarbons.
Show solution
Refer to the Samacheer Kalvi Class 11 Chemistry textbook definition.
Q2MEDIUM· Application
Give two examples of hydrocarbons from daily life and explain.
Show solution
Students should draw from familiar, local examples relevant to alkanes, alkenes, alkynes and aromatic compounds.
Q3HARD· Long Answer
Explain Hydrocarbons with a neat diagram (if applicable) and state its significance.
Show solution
A complete answer includes definition, explanation, labelled diagram and conclusion.

5-minute revision

The whole chapter, distilled. Read this the night before the exam.

  • Class 11 Chemistry — Chapter 13: Hydrocarbons.
  • Core topic: Alkanes, alkenes, alkynes and aromatic compounds.
  • Describe reactions of alkanes, alkenes and alkynes.
  • Explain aromaticity and substitution in benzene.

Tamil Nadu (TNBSE) marks blueprint

Where the marks come from in this chapter — so you can plan your prep.

Typical chapter weightage: Carries marks in the TN HSC Public Exam through MCQs, short-answer and long-answer (5-mark) questions

Question typeMarks eachTypical countWhat it tests
MCQ11-2Definitions and key facts
Short Answer2-31-2Explanation and examples
Long Answer51Detailed explanation, diagram and application
Prep strategy
  • Read and understand all definitions in Chapter 13
  • Memorise key formulas and their units
  • Practice past-paper questions from this chapter
  • Draw and label all diagrams from the Samacheer Kalvi textbook

Where this shows up in the real world

This chapter isn't just an exam topic — it lives in the world around you.

Everyday application of Hydrocarbons

Concepts from hydrocarbons are applied widely in daily life and professional fields.

Exam strategy

Battle-tested tips from teachers and toppers for this chapter.

  1. Read the question carefully before answering
  2. Write definitions precisely and use technical vocabulary
  3. Draw labelled diagrams wherever applicable
  4. Show all steps in numerical problems for full marks

Going beyond the textbook

For olympiad aspirants and curious learners — topics that build on this chapter.

  • Explore advanced problems on hydrocarbons from Olympiad resource books.
  • Look for cross-connections between this chapter and other subjects.

Where else this chapter is tested

CBSE board isn't the only one — other exams test this chapter too.

TN HSC Public ExamHigh
School Unit TestsHigh
NTSE / Olympiad (Classes 9–12)Medium

Questions students ask

The real ones — pulled from the Q&A community and tutor sessions.

This chapter focuses on alkanes, alkenes, alkynes and aromatic compounds as part of the Class 11 Samacheer Kalvi Chemistry curriculum.

Carries marks in the TN HSC Public Exam through MCQs, short-answer and long-answer (5-mark) questions
Verified by the tuition.in editorial team
Last reviewed on 3 June 2026. Written and reviewed by subject-matter experts — read about our process.
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