CBSE 9 Science · U4
Earth as a System
Syllabus-listed 5-mark theory unit covering Earth as an interconnected system, solar radiation, the electromagnetic spectrum, interaction of radiation with Earth's surface, differential heating, winds, biogeochemical cycles, and human impact on natural cycles.
Test yourself
A focused, distraction-free run through 25 multiple-choice questions. Hints if you need them; your score at the end.
Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Topic 4.1
Earth as an Interconnected System
Earth spheres, interactions among atmosphere, hydrosphere, geosphere, cryosphere and biosphere.
Topic 4.2
Solar Radiation and the Electromagnetic Spectrum
Nature of solar energy, electromagnetic waves, visible light, reflection, absorption and heating.
Topic 4.3
Differential Heating and Winds
Unequal heating, pressure differences, air movement, land breeze, sea breeze, mountain breeze and valley breeze.
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Topic 4.4
Biogeochemical Cycles
Water, carbon, oxygen and nitrogen cycles as matter movement between living and non-living parts.
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Topic 4.5
Human Impact on Earth Systems
Human influence on cycles, air and water quality, land use, climate and environmental balance.