Question 5)
1 Hour: 100g
40 Minutes: 50g
20 Minutes: 25g
0 Minutes: 12.5g
Question 6)
160 Days: 80ou
120 Days: 40ou
80 Days: 20ou
40 Days: 10ou
0 Days: 5ou
Every period of time, the radioactive isotopes halve in numbers as they emit radiation.
I think you now know the gist. Try doing the rest yourself.
Good luck.