At standard temperature and pressure, oxygen is colourless, odorless and tasteless gas with molecular formula O, referred to as dioxygen ,two oxygen atoms are chemically bound with each other. Oxygen is an element that can be Solid Liquid or Gas depending on its temperature and pressure. In the atmosphere it is found as a Gas, specifically known as a diatomic gas. Both oxygen atoms and oxygen gas are reactive substances that are essential for life.
Reactivity-Oxygen gas reacts with every element except noble gases. The product of those reactions are called oxides. With magnesium, oxidation occurs at standard temperature and pressures, while heavier elements require high temperature and pressure to force oxidation. Although oxygen gas itself is not flammable on its own, it is essential for combustion. In the heat treatment plants oxygen gas is used to increase their burning temperature. In atmospheric air, percentage of oxygen is 20.9% (Approx.),N2 is 79% , Ar is about 0.08% and the remaining are CO2, CO, other suspended particular maters.