The top row of boxes is " F O R C E " .
Answer:
8.61 min
Explanation:
original mass= 12.65
first half life = 12.65/2 = 6.325
second half life = 6.325/2 = 3.1625
Note : 3.1625 is the closest to the value (3.115) given so we work with it
total time for decay =17.22
therefore two decays = 17.22/2= 8.61
The Canadian Shield<span>, also called the Laurentian Plateau, or Bouclier canadien (French), is a large area of exposed Precambrian igneous and high-grade metamorphic </span>rocks<span> (geological </span>shield<span>) that forms the ancient geological core of the North American continent (the North American Craton or Laurentia).</span>
