Questions are listed in attached picture Brief Overview of Activity: Radioactive
ID: 3898236 • Letter: Q
Question
Questions are listed in attached picture
Brief Overview of Activity: Radioactive decay is one of the sources of the heat that drive the Earth's geologic activity. Radioactive decay also allows us to date rocks and determine the age of the Earth and other solar system bodies. Required Items:36 coins, a calculator, pencil & paper. Procedure: In this activity you will simulate the radioactive decay of 36 atoms of a rare isotope of uranium, U-235. Uranium-235 has a half-life of 700 million years. Gather 36 coins and arrange them In a 6 times 6 grid with all of the coins facing heads up. Flip each coin once and place it back in its original location. This represents the passage of 1 half-life (700 million years for this example). The coins that came up heads represent atoms that have not yet decayed; the coins that came up tails represent atoms that have decayed. Record the number of heads below. Next flip each one of the remaining heads-up coin once and place it back in its original location. 1.4 billion years have now passed by (2 times 700 million). Record the number of remaining heads below. Repeat this process until all coins are tails up. _______ Original number of U-235 atoms _______ Remaining number of U-235 atoms 1st flip. _______ Remaining number of U-235 atoms after 2nd flip Add additional lines as needed. How many half-lives did it take for all of the atoms to decay? How many years does that equate to? Do you think everyone in class will get the same answer? Why?Explanation / Answer
I think there's a slight mistake in the question and you have to flip half of the heads-up coins each time. This is because half-life is "the time taken for the radioactivity of a specified isotope to fall to half its original value". I have assumed this and solved below accordingly.
36 : original no. of U235 atoms.
18: no. of U235 atoms after 1st flip.
9: no. of U235 atoms after 2nd flip
Keep on halfing so the series looks like:
36 18 9 4.5 2.25 1.125 0.5625
Flooring the decimals:
36 _18_ 9_ 4_ 2_ 1_ 0
Each flip ( represented above by _ ) is equal to one half life or 700 million years.
A)Thus it takes 6 half lives for all the atoms to decay.
B) 6 half-lives = 6*700 million years = 42 Million years
C) Yes, everybody in the class will get the same result. Because the everybody will get the same no. of heads-up coins after each flip.
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