The half-life of Plutonium−239, t1/2 is 2.41 × 10⁴<span> yrs
time taken to reach tolerable level = seven half-lives
= 7 x t1/2
= 7 x </span>2.41 × 10⁴ yrs
= 168700 yrs
= 1.687 x 10⁵ yrs
Hence, the period of time that <span>Plutonium-239 must be stored is </span>1.687 x 10⁵ years.
<span>When a
substance is heated, its atoms gain
energy and begin to vibrate rapidly within the lattice
of the substance (the substance expands). As more heating continues, the atoms
gain even more energy and move more rapidly until they are able to overcome the
force of the bonds, that hold the atoms together
in the lattice, until the structure is disrupted. </span>
Answer:
Explanation: In the previous section we listed four characteristics of radioactivity and nuclear decay that form the basis for the use of radioisotopes in the health and biological sciences. A fifth characteristic of nuclear reactions is that they release enormous amounts of energy. The first nuclear reactor to achieve controlled nuclear disintegration was built in the early 1940s by Enrico Fermi and his colleagues at the University of Chicago. Since that time, a great deal of effort and expense has gone into developing nuclear reactors as a source of energy. The nuclear reactions presently used or studied by the nuclear power industry fall into two categories: fission reactions and fusion reactions
The empirical formula of metal iodide : CoI₃(Cobalt(III) Iodide)
<h3>Further explanation</h3>
13.02 g sample of Cobalt , then mol Co(MW=58.933 g/mol) :

Mass of metal iodide formed : 97.12 g, so mass of Iodine :

Then mol iodine (MW=126.9045 g/mol) :

mol ratio of Cobalt and Iodine in the compound :