What is the physical state of water at 100 degree Celsius?
You can not know the answer to that question. First of all, it depends on the ambient pressure. If the ambient pressure is less than one standard atmosphere, then the state of the water will be gas. If the ambient pressure is more than one standard atmosphere, then *MOST* of the water will be liquid, but if there is any space above the surface of the liquid, then there will be some gas-phase water molecules in that space. If the ambient pressure is exactly one standard atmosphere, then the water could be boiling, or it could be condensing from steam, or it could be that the gas and liquid phases are in equillibrium. Any way you look at it though, there will be gas present, and there will be liquid present.
