Radioactive element X has a half-life of 30 days. A

spazzter08dyk2n

spazzter08dyk2n

Answered question

2022-05-08

Radioactive element X has a half-life of 30 days. A rock sample contains 4 grams element X when it forms. How many half-lives will have elapsed in 90 days? How much of the original amount of X will be unchanged after 90 days?

Answer & Explanation

partyjnopp9wa

partyjnopp9wa

Beginner2022-05-09Added 17 answers

Given that radioactive element X has a half-life 30 days
Hence the number (n) of half-lives in 90 days
n = 90 30
n=3
The amount N of radioactive element X left after n=3 half-lives with initial amount N 0 = 4 g m
N = N 0 ( 1 2 ) n
= 4 ( 1 2 ) 3
= 4 8
=0.5
hence the amount left after 90 days or 3 half-lives will be 0.5 grams

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