element
Natural polonium exist probable as a compound (as PoPb) but this hypothesis was not surely confirmed up today.
Mixture
The chemistry of polonium is not known in details but I suppose that this element is oxygen.
No, energy is NOT an element, a compound or a mixture.
electricity is not a compound, mixture or element.
electricity is not a compound, mixture or element.
electricity is not a compound, mixture or element.
Oxygen, Hydrogen, halogens
It is a mixture.
Oxygen, hydrogen, halogens
Very probable this element is oxygen.
Is gasoline a element a mixture or a compound