Answer:
-> there isnt an exact answer
Explanation:
stars have a cycle of life, like humans and other organisms. when they are dying they may get hotter or bigger. they will become red giants, and may explode.. kinds like the big bang theory. it will leave a small white dwarf star behind, about the size of earth, and it is super hot. the stars contain dark matter which will be spewed into the galaxy planting a path for future stars
I reccomend searching google for an exact answer
Answer :
121.5 <span>
μCi
Explanation : We have Ce-141 half life given as 32.5 days so if the activity is 3.8 </span><span>μci after 162.5 days of time elapsed we have to find the initial activity.
We can use this formula;
</span>

3.8 /

=

((0.693 X 162.5 ) / 32.5) = 121.5
<span>
On solving we get, The initial activity as 121.5 </span>μci
Molecular mass of H2O is: 16+2*1=18
so moles of 40g of H2O is: 40/18=2.22
A. 1 proton and 1 neutron