Asample of rock is found to contain 100 grams of a parent isotope. how many grams of the parent isotope will remain after two half-lives?
answer

50

100

75

25

Option D - 25

Step-by-step explanation:

Given : A sample of rock is found to contain 100 grams of a parent isotope.

To find : How many grams of the parent isotope will remain after two half-lives.

Solution : A sample of rocks contain parent isotope  = 100 gram

After one half life of the parent isotope i.e. divided by 2

After two half lives of the parent isotope means again divide one-half life by 2

Which means 25 gram of the parent isotope will remain after two half lives.

Therefore, Option D is correct -25

a) 0.25x times 3. (could be wrong on equation.)

b) 2.25 pound of dark chocolate. (can i eat all the chocolate? plz? anyway, again, could be wrong, but i hope im right. all the chocolate together should be 5.25 pounds)

have a good day!

-2 is the right