How much uranium-235 woud be left if a fossil were 700 million years old?

Question

Possible answers:

0mg

40 mg

60 mg

Answer 1

0mg

Answer 2

exactly half of the fossil's mass

Answer 3

Well...

Half-life of U235 is 700 Million years.

So 50% of what you started with, which we don't know!

Answer 4

you didnt say how many mg's it had to begin with. not enough info.

Answer 5

half of the original amount.

.... so whats the original amount?

Answer 6

who cares sounds boring to me