Question 12(e)
Hydrogen is
- combustible
- non-combustible
- supporter of combustion
- neither supporter nor combustible
combustible
Reason — Hydrogen is combustible in nature, burns with a pale blue flame but is a non-supporter of combustion.
Key Concepts Covered
This question tests your understanding of the following concepts from the chapter Hydrogen: Question, Hydrogen, Combustible, Non, Supporter, Combustion. 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.
Practice more questions from Hydrogen — Chemistry, Class 8 ICSE
Hydrogen — Interactive Study Guide
Quick Concept Map
PREPARATION: Zn + dil. H2SO4 → ZnSO4 + H2↑
TEST: Pop test (burns with a pop sound)
PROPERTIES: Colourless, odourless, lightest gas, reducing agent
WATER OF CRYSTALLISATION: Fixed water molecules in a crystal (e.g., CuSO4.5H2O)
Lab Preparation Summary
| Item | Detail |
|---|---|
| Reactants | Zinc granules + Dilute sulphuric acid |
| Word equation | Zinc + Dilute sulphuric acid → Zinc sulphate + Hydrogen |
| Apparatus | Flat-bottomed flask, thistle funnel, delivery tube, gas jar, trough |
| Collection | Downward displacement of water (H2 is insoluble) |
| Drying agent | Concentrated H2SO4 |
| Test | Pop test — burns with a “pop” sound |
Key Reactions of Hydrogen
| Reaction | Word Equation | Type |
|---|---|---|
| Combustion | Hydrogen + Oxygen → Water | Combination |
| Reducing CuO | Copper oxide + Hydrogen → Copper + Water | Redox |
| With chlorine | Hydrogen + Chlorine → Hydrogen chloride | Combination |
| Haber process | Hydrogen + Nitrogen → Ammonia | Combination |
Water of Crystallisation — Key Data
| Common Name | Formula | Colour | H2O Molecules |
|---|---|---|---|
| Blue vitriol | CuSO4.5H2O | Blue → White (on heating) | 5 |
| Green vitriol | FeSO4.7H2O | Green | 7 |
| Washing soda | Na2CO3.10H2O | White | 10 |
| Gypsum | CaSO4.2H2O | White | 2 |
| Epsom salt | MgSO4.7H2O | White | 7 |
Hydrogen as Clean Fuel
| Advantages | Challenges |
|---|---|
| Highest calorific value (150,000 kJ/kg) | Highly explosive — difficult to store |
| Only product is water — zero pollution | Expensive to produce |
| Can be made from water (renewable) | No fuelling station infrastructure |
| Fuel cells generate electricity directly | Needs very high pressure or low temperature for storage |
Self-Check Questions
- Name the acid and metal used in the lab preparation of hydrogen.
- How is hydrogen gas tested? What is this test called?
- Why is hydrogen called a reducing agent?
- What happens when blue copper sulphate crystals are heated? Is this reversible?
- State two advantages and two challenges of using hydrogen as a fuel.