Natural Resources
Air, Water, Soil, Minerals and Conservation
Overview
Natural Resources forms a consistently tested topic in UTET Paper II Science, connecting physical science concepts with environmental awareness. This topic bridges chemistry (composition of air, water properties), earth science (soil formation, mineral deposits) and environmental studies (conservation practices). Questions typically test factual recall of resource composition, understanding of cycles (water cycle, nitrogen cycle) and application of conservation principles.
For Uttarakhand-specific context, expect questions linking to the state's Himalayan ecosystem — glacial water sources like Gangotri and Yamunotri, mineral deposits in the hills and forest conservation movements like Chipko. Mastery requires knowing both scientific facts and their real-world environmental implications.
Key Concepts
- Natural resources are materials obtained from nature that satisfy human needs — classified as renewable (air, water, forests) and non-renewable (minerals, fossil fuels).
- Air composition: Nitrogen 78%, Oxygen 21%, Argon 0.93%, Carbon dioxide 0.04%, with traces of water vapour, dust and pollutants.
- Water cycle (Hydrological cycle): Evaporation → Condensation → Precipitation → Collection — a continuous process driven by solar energy.
- Soil formation occurs through weathering of rocks over thousands of years, involving physical (temperature, wind), chemical (oxidation, hydration) and biological (lichens, roots) processes.
- Soil profile consists of four horizons: O (organic/humus), A (topsoil), B (subsoil), C (weathered rock), and R (bedrock).
- Minerals are naturally occurring inorganic substances with definite chemical composition — classified as metallic (iron, copper, gold) and non-metallic (limestone, ite, coal).
- Conservation means judicious use of resources to ensure availability for future generations — the principle of sustainable development.
- Biogeochemical cycles (carbon, nitrogen, oxygen cycles) maintain the balance of elements essential for life on Earth.
Formulas / Key Facts
| Resource | Key Facts to Remember |
|---|---|
| Air | Nitrogen (78%) — used by plants via nitrogen fixation; Oxygen (21%) — supports respiration and combustion |
| Water | 97% saline (oceans), 2% frozen (glaciers), only 1% freshwater available for use |
| Soil types in India | Alluvial (most fertile, Gangetic plains), Black/Regur (cotton, Deccan), Red (iron-rich), Laterite (heavy rainfall areas), Mountain (Uttarakhand hills) |
| Major minerals | Iron ore — Jharkhand, Odisha; Coal — Jharia, Raniganj; Petroleum — Mumbai High, Assam |
| Uttarakhand resources | Glaciers (Gangotri, Pindari), limestone deposits, magnesite, soapstone, forest cover ~45% |
Water conservation methods: Rainwater harvesting, drip irrigation, watershed management, check dams
Soil conservation methods: Contour ploughing, terrace farming (common in Uttarakhand hills), afforestation, crop rotation
Air pollution control: Using CNG, electrostatic precipitators, catalytic converters, planting trees
Worked Examples
Example 1: Soil Profile Identification
Question: Arrange the soil horizons from top to bottom: Subsoil, Bedrock, Topsoil, Weathered rock.
Solution:
- Step 1: Recall the standard soil profile sequence
- Step 2: Topsoil (A horizon) — uppermost layer with humus
- Step 3: Subsoil (B horizon) — below topsoil, contains minerals leached from above
- Step 4: Weathered rock (C horizon) — partially broken parent rock
- Step 5: Bedrock (R horizon) — unweathered solid rock at bottom
Answer: Topsoil → Subsoil → Weathered rock → Bedrock
Example 2: Water Distribution Calculation
Question: If Earth has 100 units of water, how much is available as usable freshwater?
Solution:
- Total water = 100 units
- Saline water (oceans) = 97 units
- Frozen water (ice caps, glaciers) = 2 units
- Freshwater available = 100 − 97 − 2 = 1 unit
Answer: Only 1% of Earth's water is usable freshwater (groundwater, rivers, lakes).
Example 3: Nitrogen Cycle Application
Question: How does nitrogen in the atmosphere become available to plants?
Solution:
- Step 1: Atmospheric nitrogen (N₂) cannot be used directly by plants
- Step 2: Nitrogen-fixing bacteria (Rhizobium in legume roots, Azotobacter in soil) convert N₂ to ammonia (NH₃)
- Step 3: Nitrifying bacteria convert ammonia to nitrites, then nitrates
- Step 4: Plants absorb nitrates through roots
- Step 5: Lightning also fixes some atmospheric nitrogen
Answer: Through biological nitrogen fixation by bacteria and atmospheric fixation by lightning.
Common Mistakes
| Wrong Thinking | Correct Understanding |
|---|---|
| "Oxygen is the most abundant gas in air" | Nitrogen is most abundant (78%); oxygen is second (21%) |
| "All water on Earth can be used for drinking" | Only about 1% is accessible freshwater; 97% is saline, 2% frozen |
| "Soil is just crusite rock" | Soil contains mineral particles, humus, water, air and living organisms — it's a complex ecosystem |
| "Minerals are renewable because they're natural" | Minerals take millions of years to form — they are non-renewable resources |
| "Conservation means not using resources at all" | Conservation means sustainable and judicious use, not complete avoidance |
| "The water cycle only involves evaporation and rain" | Water cycle includes evaporation, transpiration, condensation, precipitation, infiltration and runoff |
Quick Reference
- Air: N₂ (78%) + O₂ (21%) + Ar (0.93%) + CO₂ (0.04%)
- Usable freshwater: Only 1% of total Earth's water
- Soil horizons (top to bottom): O → A → B → C → R
- Three R's of conservation: Reduce, Reuse, Recycle
- Uttarakhand connection: Chipko Movement (1973) — forest conservation; Gangotri glacier — Ganga's source
- Nitrogen fixation agents: Rhizobium (legumes), Azotobacter (free-living), lightning