You started with 64 g of a radioactive substance. if you have 4.0 g of that substance left, then how many half-lives have elapsed?
a.2
b.3
c.4
d.5

C) 4

Explanation: Half life is the time in which the amount of a radioactive substance remains halve of its initial amount. For example, half life of carbon-14 is 5730 years. It means if we have 4 grams of carbon-14 then it will remain 2 grams after 5730 years.

For the given problem, the initial amount of a radioactive substance is 64 grams, if 4.0 grams of that substance left, then how many half-lives have elapsed.

So, Its asking to calculate the number of half-lives. The formula used for this is:

where, A0 is the initial amount and A is final amount and n is the number of half-lives.

Let's plug in the values in the formula.

n = 4

So, there will be 4 half-lives and hence C is the correct choice.

elements

explanation:

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a plasma is a warm ionized gasoline consisting of approximately equal numbers of definitely charged ions and negatively charged electrons. the characteristics of plasmas are notably unique from the ones of ordinary neutral gases in order that plasmas are considered a awesome "fourth kingdom of remember."