Natural Resources

Overview

Natural Resources form a foundational topic in upper-primary science, connecting physical sciences with environmental awareness. For PSTET Paper II, this topic tests both factual knowledge about air, water, soil and minerals, and understanding of conservation principles that align with NCF's emphasis on environmental education.

Questions typically appear in two forms: direct recall (composition of air, types of soil, mineral classification) and application-based (conservation methods, pollution effects, sustainable practices). Mastering this topic requires understanding the interconnections between resources—how deforestation affects soil, how water pollution impacts the water cycle, and how mineral extraction affects land and air quality. Punjab-specific context (groundwater depletion, stubble burning, canal irrigation) adds regional relevance.

Key Concepts

• **Natural resources are classified as renewable and non-renewable.** Renewable resources (air, water, soil, forests) can be replenished naturally within a human lifetime. Non-renewable resources (minerals, fossil fuels) take millions of years to form and are finite.

• **Air is a mixture, not a compound.** It contains approximately 78% nitrogen, 21% oxygen, 0.03% carbon dioxide, and traces of other gases plus water vapour. The composition remains fairly constant up to 80 km altitude.

• **The water cycle is a closed system.** Water continuously moves through evaporation, condensation, precipitation and collection. Human activities do not destroy water but can render it unusable through pollution.

• **Soil is a living resource formed over centuries.** It consists of weathered rock, organic matter (humus), air, water and living organisms. Topsoil formation takes approximately 1000 years per 2-3 cm.

• **Minerals are naturally occurring inorganic substances with definite chemical composition.** They are extracted through mining (underground, open-pit) and are non-renewable. India has significant deposits of iron ore, coal, mica and bauxite.

• **Conservation means wise and sustainable use, not merely preservation.** It involves reducing consumption, reusing materials, recycling waste and restoring degraded resources.

• **The three Rs hierarchy prioritises Reduce over Reuse over Recycle.** Reduction at source is most effective; recycling is a last resort before disposal.

Key Facts

| Resource | Key Facts for Examination | |----------|---------------------------| | **Air** | Oxygen supports combustion and respiration; nitrogen dilutes oxygen preventing spontaneous fires; CO₂ at 0.03% is essential for photosynthesis but excess causes greenhouse effect | | **Water** | 97% saline (oceans), 2% frozen (ice caps), only 1% available as freshwater; groundwater is the largest freshwater source accessible to humans | | **Soil** | Three main types: sandy (large particles, poor water retention), clayey (fine particles, high water retention), loamy (ideal mixture for agriculture) | | **Minerals** | Metallic (iron, copper, gold) and non-metallic (coal, petroleum, salt); India ranks among top producers of iron ore, coal and mica |