Answer:
The answer to your question is: 56.25 g of Uranium
Explanation:
Data
mass = 3600 g of Uranium 235
half life = 40000 years
How much after 240 000 years
3600 g of Uranium right now
1800 g 40 000 years
900 g 80 000 years
450 g 120 000 years
225 g 160 000 years
112.5 g 200 000 years
56.25 g 240 000 years