Is kryptonite radioactive?

In Superman comics, one of the few things that can defeat Superman is a strange metal called Kryptonite that comes from the planet Krypton. Although the gas krypton exists in air, kryptonite does NOT.

It depends on the isotope, of which carbon has three that occur naturally. Carbon-12 (about 99%) and carbon-13 (about 1%) are not radioactive; carbon-14 (trace amounts, maybe one part per...

Radioactive means unstable, so any element that has an unstable nucleus is radioactive. This is especially true of element's isotopes.

Yes. A radioactive standard is a configuration of radioactive material constructed in a precise way, allowing the standard to be used as a reference when measuring other radiation sources. Standards...

It depends. There are over 20 isotopes (types) of copper. Most of them are radioactive, but also quite rare. So any copper an average person would see would not be radioactive.