Hydrogen is an element.
It could be either. If you have, say, some radioactive caesium (an element) and you chlorinate it, you'll have the compound caesium chloride, and it will be radioactive. If you take some radioactive powdered cobalt-60 and mix it with sugar, it's a mixture (and a nasty one). In general, it is an atom or, said differently, an atom of an element, that is radioactive. The only question is whether that atom of the given element is in a pure (or elemental) form, or whether it is in a chemical compound with something, or whether it is mixed in with something else to form a mixture. Something that is radioactive is composed of (either all or in part) a radioactive nuclide (one or more) of a given element or elements that are in there.
Radioactive radiation is not a material
Radium is an element.
Hydrogen is an element.
homogeneous
It is a solution. And a solution is homogeneous.
Is wood a compound homogeneous mixture a heterogenous mixture or an element. Is steel a homogeneous mixture a heterogeneous mixture an element.
it is a compound
Concrete is a heterogeneous mixture.
homogeneous
homogeneous
homogeneous
heterogeneous mixture
It is a solution. And a solution is homogeneous.
Heterogenous
heterogeneous
heterogeneous
Is wood a compound homogeneous mixture a heterogenous mixture or an element. Is steel a homogeneous mixture a heterogeneous mixture an element.
compound
compound
it is a compound