After three half- lives, a sample contains 10 grams of parent isotopes. how many grams of the parent isotope were present to start?

its not for its for earth/space science

Initial amount of parent isotope present in the sample was 80 grams.

Explanation: Initial amount was= 80 grams

The sample undergone radioactive decay and after first half-life, it has= 40 grams (half of initial amount)

after second half-life, it has= 20 grams

And after third half-life, it has= 10 grams

Thus, the sample at present has 10 grams and initially had 80 grams of the parent isotope materials.