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 and petroleum ether are confused by most people because of the similarity in names. Though their names are bit similar and both are liquids, they are completely different chemicals and have different uses.etroleum ether is a mixture of hydrocarbon compounds. This is a highly flammable and volatile liquid. The liquid is colorless. Petroleum ether is a nonpolar solvent. Though its name says ether, it doesnât have compounds with ether linkages. Petroleum ether is produced during the petroleum refining process.