sci_chem
Water Treatment
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.
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Chemistry · CBSE 10 · ICSE 10 · GCSE (AQA, Edexcel, OCR)
Summary
Tap water carries dissolved minerals within safe limits, so it conducts electricity and has taste. Pure (deionised) water has no dissolved substances and is only for the lab.
Each stage removes a different impurity: grids catch debris, a coagulant sinks fine mud, sand beds strain grit, and chlorine kills germs. Skip a step and something harmful gets through.
Distillation boils water off and leaves salt behind. Reverse osmosis pushes water through a fine membrane that blocks salt ions, and is cheaper on energy.
Solids settle as sludge; bacteria break down the rest. The sludge is digested without air to make biogas, which fuels the works.
Hard words & meanings
| potable water | water that is safe to drink, with dissolved salts and microbes within safe limits |
| sedimentation | letting suspended particles settle out of water under gravity |
| coagulant | a chemical such as aluminium sulfate that makes fine particles clump together and sink |
| flocculation | the clumping of fine particles into larger flocs after a coagulant is added |
| chlorination | adding chlorine to water to kill harmful bacteria and viruses |
| desalination | removing dissolved salts from seawater to make it drinkable |
| reverse osmosis | forcing water through a semi-permeable membrane under pressure to leave salt behind |
| sewage | wastewater from homes and industry that must be treated before discharge |
Model exam answers, grammar & audio
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