can I get some help? I'll give out a metal.

A sample 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?

100

75

50

25

I know the answer isn't 50, that's what I put & got it wrong.

Question

can I get some help? I'll give out a metal.

A sample 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?

 100

 75

 50

 25

I know the answer isn't 50, that's what I put & got it wrong.

anonymous · Answer

@ParthKohli @quietus @braden_foster_1 @Love.Kat123 @Mandre @xoalybabyxo @MonaLove @DangerousJesse @ganeshie8 @Gabylovesyou

quietus · Answer

two halves = 1 quarter so 100 x 1/4 = 25?

dangerousjesse · Answer

After two half-lives, the sample will have been "halved" twice. Therefore, there would be 25 grams of the parent isotope.

dangerousjesse · Answer

@quietus, two halves don't equal one quarter mathematically, they equal one whole. you merely halve the parent isotope the amount of times the question says the lives have been halved.

quietus · Answer

i meant |dw:1403984957686:dw| but anyway the answer is 25 :)