The commonalities that elements, compounds, and mixtures all have in common is that they all contain atoms. Even though they all contain atoms, the number of atoms vary in each of them.
It is a mixture
It is a compound: NaCl-sodium [an element] bonded to chloride [an element].
Mixture
No, an element is not a mixture.
An element - substance - NOT a mixture.
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.
a mixture
Is a mixture
Brass is a mixture of copper and zinc. It is not an element on its own.