Colour of FeO is:A. BlackB. BlueC. GreenD. Red

To determine the color of FeO (iron(II) oxide), we need to consider its chemical composition and the nature of the iron oxidation state in the compound.

Explanation:
Chemical Composition:
FeO consists of iron (Fe) in the +2 oxidation state and oxygen (O) in the -2 oxidation state.
Color Characteristics:
The color of metal oxides can vary significantly depending on the oxidation state of the metal and its interaction with light.
Iron(II) oxide (FeO) is known to be a black solid.
Conclusion:
Thus, the correct answer is:

A. Black

FeO is commonly recognized for its black coloration, which is characteristic of many transition metal oxides, particularly those of iron in lower oxidation states.