Radioactive decay which is a property of several elements found on the earth involves the emission of charged particles and energy of unstable nuclei of radioactive atoms, thereby becoming stable with time. The rate of radioactive decay is often referred to as half-life of that element, and could be as more than millions of years. Radioactive elements that undergo radioactive decay have made it possible for a more accurate dating to be achieved using the known decay rates of radioactive materials.
Xylem, plant vascular tissue that conveys water and dissolved minerals from the roots to the rest of the plant and also provides physical support. Xylem tissue consists of a variety of specialized, water-conducting cells known as tracheary elements.
