How much of a radioactive kind of iodine will be left after 42 hours if the half-life is 21 hours and you start with 120 grams?

30 grams

Step-by-step explanation:

If the half life is 21 hours, that means after 21 hours, the initial amount will decrease to half.

So, since we started with 120 grams, it will be at 60 grams after 21 hours.

After another 21 hours have passed (after a total of 42 hours), the amount of 60 grams will split in half again to 30 grams.

So, after 42 hours, there will be 30 grams left of the radioactive iodine

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this excerpt is taken from the book “we shall not be moved : the women’s factory strike of 1909 “ and is written by joan dash. it is the story of the great strike when almost 30thousand women working in factories in america formed a union to fight unsafe working conditions, long working hours and miserable wages.

question: which best states the author’s purpose for including this information in the text?

answer: to challenge the reader’s ideas about a historical event