What is an example of a radioactive rate earth metal in the periodic table ?

All isotopes of promethium are radioactive, and it does not occur naturally in the earth's crust; however, a trace amount is generated by decay of uranium 238. They are often found in minerals with thorium, and less commonly uranium

Explanation:

Explanation:  All isotopes of promethium are radioactive, and it does not occur naturally in the earth's crust; however, a trace amount is generated by decay of uranium 238. They are often found in minerals with thorium, and less commonly uranium.

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