Question

which phrase describes one characteristic of radioactive elements?
are produced in a laboratory
decay at a constant rate
have a consistent number of particles
release energy and particles to maintain radioactivity

Explanation:

• Radioactive elements decay at a constant rate (half - life concept). Some are naturally occurring (not all produced in lab). During decay, particle number changes (e.g., alpha decay loses 2 protons and 2 neutrons). Radioactive decay releases energy and particles to become more stable (not to maintain radioactivity).

Answer:

decay at a constant rate