中学理科（化学）：水の生成の反応式「2H₂＋O₂→2H₂O」のO₂が、なぜOだとダメかということに納得できない方へ

THE WATER CYCLE The water cycle, also known as the hydrological cycle, is the continuous movement of water on, above, and below the surface of the Earth. It plays a critical role in shaping geological processes, regulating climate, and sustaining ecosystems. The cycle ensures that water is constantly recycled between the atmosphere, lithosphere, hydrosphere, and biosphere. MAIN PROCESSES IN THE WATER CYCLE 1. EVAPORATION When the sun heats up water from oceans, rivers, and lakes, it changes into