He will use a radioactive element with a long half life of greater than 1 billion years
Explanation:
Rocks are an aggregation of solid mass which is usually rich in minerals. The age of rocks is established using radiometric dating method.
According to Oxford Dictionary, radiometric dating is "a method of dating geological specimens by determining the relative proportions of particular radioactive isotopes present in a sample."
The age of rocks can only be ascertained using isotopes that have very long half lives because many of these rocks are very old (aged billions of years) hence their age can only be determined using elements that has a half life greater than 1 billion years.
Gel electrophoresis is a process or a technique in which fragments of DNA are separated in terms of their sizes.
<em><u>The restriction enzyme is mixed with a DNA sample before the process. The restriction enzyme cut DNA at specific points into fragments which can then be separated based on their sizes on an agarose gel.</u></em>
When current is applied to the gel DNA move towards the positively charged electrode since DNA is negatively charged, with shorter fragments migrating faster through the gel in comparison with large fragments.
The ozonosphere is another term for the ozone layer, which is within the Earth's stratosphere. The ozone layer is responsible for absorbing most of the sun's ultraviolet (UV) radiation, thanks to its high concentration of ozone that is exclusive to this layer.
