D. all of these can produce nuclear energy
There is 3800 mmHg in 5 atm
3.62x10^24/ 6.02x10^23= 6.013 moles to 3dp
The mass decay rate is of the form

where
m₀ = 3000 g,the initial mass
k = the decay constant
t = time, years.
Because the half-life is 30 years, therefore

After 60 years, the mass remaining is

Answer: 750 g
The answer to 4 is A.
The answer to 5 is C.