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

  • 1Describe group 15–18 trends
  • 2Explain important oxoacids, oxyacids and uses of noble gases
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Why this chapter matters
p-Block Elements – II is an important chapter in Class 12 Chemistry (Samacheer Kalvi). It covers group 15, 16, 17 and 18 elements and their 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.

p-Block Elements – II — Class 12 Chemistry (Samacheer Kalvi)

TN State Board (Samacheer Kalvi) Class 12 Chemistry, Chapter 3. Group 15, 16, 17 and 18 elements and their compounds.


1. About this chapter

This chapter covers p-Block Elements – II as part of the Class 12 Samacheer Kalvi Chemistry curriculum. It deals with group 15, 16, 17 and 18 elements and their compounds and builds conceptual understanding essential for the TN HSC Public Exam.

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

  • Describe group 15–18 trends
  • Explain important oxoacids, oxyacids and uses of noble gases

2. Key concepts

  • Concept 1: Describe group 15–18 trends.
  • Concept 2: Explain important oxoacids, oxyacids and uses of noble gases.

3. Important terms and formulas

Term / FormulaDescription
Describe group 15–18 trends…Describe group 15–18 trends
Explain important oxoacids, oxyacids…Explain important oxoacids, oxyacids and uses of noble gases

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 p-block elements – ii.

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 3.
  2. Give two real-life examples related to p-block elements – ii.
  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 12 Chemistry — Chapter 3: p-Block Elements – II.
  • Core idea: Group 15, 16, 17 and 18 elements and their compounds.
  • Key outcomes: Describe group 15–18 trends; Explain important oxoacids, oxyacids and uses of noble gases.
  • 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 p-Block Elements – II
Refer to Samacheer Kalvi textbook
Chapter 3 — Group 15, 16, 17 and 18 elements and their compounds.
⚠️

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 3: p-Block Elements – II.
Show solution
Refer to the Samacheer Kalvi Class 12 Chemistry textbook definition.
Q2MEDIUM· Application
Give two examples of p-block elements – ii from daily life and explain.
Show solution
Students should draw from familiar, local examples relevant to group 15, 16, 17 and 18 elements and their compounds.
Q3HARD· Long Answer
Explain p-Block Elements – II 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 12 Chemistry — Chapter 3: p-Block Elements – II.
  • Core topic: Group 15, 16, 17 and 18 elements and their compounds.
  • Describe group 15–18 trends.
  • Explain important oxoacids, oxyacids and uses of noble gases.

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 3
  • 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 p-Block Elements – II

Concepts from p-block elements – ii 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 p-block elements – ii 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 group 15, 16, 17 and 18 elements and their compounds as part of the Class 12 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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