sci_chem
The Atmosphere
Chapter summary, hard words and model exam answers for ICSE Class 10 Hindi.
Free online summary and notes (ICSE Class 10 Hindi). Read it here, no PDF download needed.
About the author
Chemistry · CBSE 10 · ICSE 10 · GCSE (AQA, Edexcel, OCR)
Summary
When Earth formed about 4.6 billion years ago, volcanic gases made the first atmosphere. It was rich in CO2, like the atmospheres of Venus and Mars today.
Dissolved CO2 reacted to form carbonate rocks like limestone. Carbon also became locked in fossil fuels, lowering the CO2 level.
6CO2 + 6H2O -> C6H12O6 + 6O2. Over billions of years oxygen built up to about 21%, allowing animal life to evolve.
Burning fossil fuels adds extra CO2; farming and waste add methane. More greenhouse gas traps more heat, causing climate change.
Hard words & meanings
| atmosphere | the layer of gases surrounding the Earth |
| greenhouse gas | a gas that absorbs and re-emits infrared radiation, warming the surface; e.g. CO2, methane, water vapour |
| greenhouse effect | the warming caused by greenhouse gases trapping infrared heat in the atmosphere |
| photosynthesis | the process where plants use light to turn CO2 and water into glucose and oxygen |
| combustion | the reaction of a fuel with oxygen, releasing energy |
| carbon monoxide | a toxic gas (CO) made by incomplete combustion when oxygen is limited |
| inert | very unreactive, taking part in few or no chemical reactions |
| parts per million (ppm) | a unit for very small concentrations - how many units of a gas in a million units of air |
Model exam answers, grammar & audio
You have read the summary. The board-ready model answers, grammar notes, one-touch audio and writing practice for this chapter are part of Lipi©.
Sign in to unlockSee it, understand it, hear it read aloud, then write the exam answer with confidence, for a fraction of a tutor cost.