Conservation & Pollution
Resources are limited, so the NCERT theme across VI–VIII is conserve and protect. The headline strategy is the three Rs: Reduce (use less in the first place), Reuse (use an item again instead of discarding it) and Recycle (process waste into new products). CTET often asks candidates to classify an everyday action under the correct R — note that reusing a glass jar to store spices is reuse, while melting plastic bottles to make new ones is recycle. Pollution is the addition of unwanted/harmful substances to air, water or soil. Air pollution comes mainly from burning fossil fuels and vehicle/industry smoke, releasing carbon dioxide, sulphur dioxide and soot; effects include smog, acid rain and respiratory illness, and rising CO₂ contributes to the greenhouse effect and global warming. Water pollution comes from sewage, industrial effluents, fertiliser and pesticide run-off, and plastic; it harms aquatic life and human health. Soil pollution comes from excess chemicals, plastics and non-biodegradable waste. A key distinction students must learn: biodegradable waste (vegetable peels, paper) is broken down by microbes, whereas non-biodegradable waste (most plastics, glass) is not — which is why plastic is such a problem. The Ganga Action Plan and afforestation (planting trees) are standard NCERT examples of conservation in action; rainwater harvesting conserves water. Pedagogy: pollution is best taught through local surveys, posters, a 'segregate the dustbin' activity, and discussion of the child's own neighbourhood — value education and attitude, not just facts. How it is tested: identify the type/cause of pollution, classify waste as biodegradable or not, match an action to the correct R, and choose the most appropriate teaching activity for environmental awareness.
✅ Solved examples
✏️ Practice — try these, take hints as needed
📝 Topic test — 8 questions
Auto-graded with full solutions; saved to your dashboard. Use the calculator and formula sheet (top-right) any time.
Key Concepts — Quick Reference
Air, Water & Soil — the core facts
| Composition of air | ~78% Nitrogen · ~21% Oxygen · ~1% others (CO₂, argon, water vapour) |
|---|---|
| Water cycle | Evaporation → Condensation → Precipitation (then collection/run-off) |
| Soil profile | Topsoil (humus-rich) → Subsoil → Parent rock; formed by weathering |
| Soil types | Sandy (big particles, drains fast) · Clayey (fine, holds water) · Loamy (best for crops) |
Energy & Conservation
| Renewable (inexhaustible) | Sun, wind, water, biomass — replenished naturally |
|---|---|
| Non-renewable (exhaustible) | Coal, petroleum, natural gas — fossil fuels, finite |
| Fossil fuels | Formed from dead plants/animals buried for millions of years |
| The 3 Rs | Reduce · Reuse · Recycle — the conservation mantra |