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ICSE Class 8 Chemistry Question 15 of 15

Chemical Reactions — Question 8

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8
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Question 12

Give one example each of -

(a) A peroxide

(b) A mixed oxide

(c) A dioxide.

Answer

(a) A peroxide — Na2O2

(b) A mixed oxide — Pb3O4

(c) A dioxide — PbO2

Source: This question is from Chemical Reactions, Chemistry — Class 8, ICSE Board.

Key Concepts Covered

This question tests your understanding of the following concepts from the chapter Chemical Reactions: Question, Peroxide, Mixed, Oxide, Dioxide, Chemical Reactions. These are fundamental topics in Chemistry that students are expected to master as part of the ICSE Class 8 curriculum.

A thorough understanding of these concepts will help you answer similar questions confidently in your ICSE examinations. These topics are frequently tested in both objective and subjective sections of Chemistry papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.

How to Approach This Question

Read the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.

Key Points to Remember

  • Balance chemical equations before solving numerical problems.
  • Learn the periodic table trends and exceptions.
  • Understand reaction mechanisms, not just outcomes.
  • Use correct IUPAC nomenclature in your answers.

Related Questions from Chemical Reactions

Practice more questions from Chemical Reactions — Chemistry, Class 8 ICSE

Chemical Reactions - Study Guide | Bright Tutorials
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Chemical Reactions — Interactive Study Guide

Quick Concept Map

CHANGES: Physical (reversible, no new substance) vs Chemical (irreversible, new substance)
REACTION TYPES: Combination | Decomposition | Displacement | Double Displacement
ENERGY: Exothermic (releases heat) vs Endothermic (absorbs heat)
REDOX: Oxidation (gain O / lose H) + Reduction (lose O / gain H) happening together

Four Types of Reactions — Quick Reference

TypePatternEasy Memory AidExample
CombinationA + B → ABJoining togetherMg + O2 → MgO
DecompositionAB → A + BBreaking apartCaCO3 → CaO + CO2
DisplacementA + BC → AC + BBully kicks out the weakFe + CuSO4 → FeSO4 + Cu
Double DisplacementAB + CD → AD + CBExchange partnersNaCl + AgNO3 → AgCl + NaNO3

Signs of a Chemical Reaction

  1. Change in colour
  2. Evolution of gas (bubbles)
  3. Change in temperature (hot or cold)
  4. Formation of precipitate (insoluble solid)
  5. Change in smell
  6. Change in state
  7. Sound or light produced

Oxidation vs Reduction

OxidationReduction
Gain of oxygenLoss of oxygen
Loss of hydrogenGain of hydrogen
Example: C + O2 → CO2 (C is oxidised)Example: CuO + H2 → Cu + H2O (CuO is reduced)

Memory aid: OIL RIG — Oxidation Is Loss (of hydrogen), Reduction Is Gain (of hydrogen)

Self-Check Questions

  1. Is dissolving salt in water a physical or chemical change? Why?
  2. Classify: Iron + Copper sulphate → Iron sulphate + Copper. What type of reaction is this?
  3. What is the difference between exothermic and endothermic reactions? Give one example of each.
  4. In the reaction CuO + H2 → Cu + H2O, which substance is oxidised and which is reduced?
  5. Write word equations for one example of each: combination, decomposition, displacement, double displacement.

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