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

step-by-step explanation: yes

step-by-step explanation:

ok so im not 100% sure but you would start by adding 5.1t and 1.9t beacuse they have the same variable. that is 7t.   then add -3.6 + 1.2 which is -2.4

so then keep that as -2.4 + 7t. i apologize if this is incorrect. best luck on your test < 3