White
Ferrous oxide, also known as iron(II) oxide, is typically black in color.
it is variable
Cupric oxide is typically black in color.
Iron oxide is typically a reddish-brown color.
Sodium oxide is typically white or yellow in color.
the colour of mercuric oxide is an orange powder.
The flame color of calcium oxide is typically a brick-red or orange-red color.
Green and Black
White
NO-gas is colourless
Gold oxide is typically red or reddish-brown in color.
Iron oxide can appear in various colors depending on its form. For example, rust is a common form of iron oxide that is reddish-brown in color. Black iron oxide is commonly used as a pigment and is, not surprisingly, black in color. Yellow iron oxide is another variety, often used in paints and ceramics.