Conservation of matter - a fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system
2.The water cycle, or the hydro-logic cycle, is the continuous circulation of water within the Earth's hydrosphere. It involves the movement of water into and out of various reservoirs, including the atmosphere, land, surface water, and groundwater. This cycle is driven by radiation from the Sun. The movement of water within the water cycle is the subject of the field of hydrology. The water is a combination of processes that water goes through in nature. It can includes precipitation, infiltration, evaporation, transpiration, and condensation.
4. This would be called Cabin pressurization. Cabin pressurization is a process in which conditioned air is pumped into the cabin of the aircraft or spacecraft, in order to create a safe and comfortable environment for passengers and crew flying at high altitudes. For aircraft, this air is usually bled off from the gas turbine engines at the compressor stage, and for spacecraft, it is carried in high-pressure, often cryogenic tanks.