Question

which phrase describes radioactive decay? (1 point) the joining of small nuclei into a larger nucleus the spontaneous emission of radiation the triggering of one reaction by the products of another the splitting of a large nucleus into smaller nuclei

Explanation:

Radioactive decay is the spontaneous emission of radiation from an unstable nucleus. Splitting a large nucleus into smaller nuclei is nuclear fission. Joining small nuclei into a larger nucleus is nuclear fusion. Triggering one reaction by the products of another is a chain - reaction concept.

Answer:

the spontaneous emission of radiation