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).
Diethyl ether. Diethyl ether, or simply ether, is an organic compound in the ether class with the formula (C 2H 5) 2O. It is a colorless, highly volatile flammable liquid. It is commonly used as a solvent in laboratories and as a starting fluid for some engines.