Kerala Board Class 9 Social Science — Flashcards for Quick Revision

A: The Big Bang theory states that the universe began approximately 13.7 billion years ago from a massive explosion. This theory explains how galaxies, stars, and planets were formed over billions of yea

A: The Geocentric theory, proposed by Ptolemy, suggested that Earth was at the center of the universe and all celestial bodies (Sun, Moon, planets, stars) revolved around it. This theory was widely accep

A: Geocentric Theory (Ptolemy): Earth at center, all celestial bodies revolve around Earth, accepted for thousands of years. Heliocentric Theory (Copernicus): Sun at center, Earth and other planets revol

A: The four natural realms are: 1. Lithosphere (solid crust made of rocks and minerals), 2. Hydrosphere (realm of water including rivers, oceans, groundwater), 3. Atmosphere (thin layer of air containing

A: Lithosphere is the solid crust or hard top part of the Earth made up of rocks and minerals and covered with soil. The term comes from Greek words 'Litho' (meaning stone or rock) and 'sphaira' (meaning

A: First Order Landforms: Primary division into continents and oceans. Second Order Landforms: Mountains, plateaus, and plains formed by internal Earth processes. Third Order Landforms: Features carved b

A: The hydrological cycle is the circulation of water in different forms (liquid, solid, gaseous) between oceans, atmosphere, land surface, and living organisms. The equation is RF = RO + ET, where RF (R

A: The six stages are: 1) Evaporation - water changes from liquid to gas, 2) Transportation - movement of water vapor through atmosphere, 3) Condensation - water vapor forms droplets and clouds, 4) Preci

A: The process by which water changes from liquid to gas due to the Sun's heat. Water from land, lakes, rivers, and oceans evaporates into water vapor. Plants also lose water through transpiration.