Answer:
nitrogen, oxygen, argon, carbon dioxide, neon, helium, krypton, hydrogen, and xenon. It does not include water vapor because the amount of vapor changes based on humidity and temperature.
The equation would be NaBr
It is a scientific hypothesis. A scientific hypothesis must be testable, however there is a significantly more grounded necessity that a testable speculation must meet before it can truly be viewed as logical. This foundation comes essentially from crafted by the rationalist of science Karl Popper, and is called "falsifiability".
Answer:
Any substance that cannot be decomposed into simpler substances by ordinary chemical processes.
Another definition:
An element is the simplest pure substance which can neither be split nor built up from other simpler substances by chemical reaction
