Oxygen is one such element, which exists in nature but in a complex compound that is commonly referred to as air. The air that humans breathe is only partially made up of oxygen, with nitrogen, hydrogen and methane making up the majority of the atmosphere's volume. On the periodic table, there are 109 known elements in the universe.
And in order to cover the most of other countries, they added the 2 dominant languages of west (Spanish) and east (Arabic). I think if there was a rationale in choosing a language as the official language of UN, only Spanish and Arabic are chosen reasonably as they cover more than 50 countries in the world. I am sure the list of official languages in the UN would be quite different if the victorious countries were different.
French was widely used as a diplomatic language from the 17th century until the middle of the 20th century, when English replaced it in that role. It is still used in many international organisations, such as NATO, the UN, EU institutions, and the World Trade Organisation.