1 If the invitation says black tie, women should wear a floor-length, evening gown. 2  A tuxedo is mandatory if you're a man. 3  This is your chance to dress as if you were headed to the Oscars. 4  Black tie optional means that wearing a tuxedo or long evening gown is not mandatory, but guests should feel free to do so.
Ether is an organic functional group consisting of a disubstituted oxygen, or an oxygen atom bonded to 2 carbon atoms (if adjacent to a ketone, functional group is then called an ester).
Ether! Although ether is no longer used as a numbing agent in surgeries, it still has many uses today. For example, ether is used in the manufacturing process of many fragrances or it may be used as starter fluid for engines. We'll delve further into the uses of ether later, but let's take a moment now to look at the structure of ether.