Radioactive elements are produced in nature and scientific experiments.

This rock is radioactive, so care must be taken when handling it.

Polonium is one of the radioactive elements.

He ate one apple.

Hydrogen is the most abundant element in the universe.

Education about sex is very important.

Sufficient caution is necessary when handling radioactive materials.

This area is off-limits due to high radiation levels.

This radio is emitting music.

This area is seriously contaminated with radioactive isotopes.