part 1 : the final volume : 1.404 L
part 2 : the initial concentration : 4.06 M
<h3>Further explanation
</h3>
Dilution is the process of adding a solvent to get a more dilute solution.
The moles(n) before and after dilution are the same.
Can be formulated :
M₁V₁=M₂V₂
M₁ = Molarity of the solution before dilution
V₁ = volume of the solution before dilution
M₂ = Molarity of the solution after dilution
V₂ = Molarity volume of the solution after dilution
part 1 :
M₁=44.8%
V₁=0.73 L
M₂=23.3%

part 2 :
V₁=739 ml=0.739 L
V₂=1.5 L
M₂=2

Answer: It will take 29 years for a 10.0-gram sample of strontium-90 to decay to 5.00 grams
Explanation:
Radioactive decay process is a type of process in which a less stable nuclei decomposes to a stable nuclei by releasing some radiations or particles like alpha, beta particles or gamma-radiations. The radioactive decay follows first order kinetics.
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
Half life is represented by 

= rate constant
Given : Strontium-90 decreases in mass by one-half every 29 years , that is half life of Strontium-90 is 29 years.
As half life is independent of initial concentration, it will take 29 years for a 10.0-gram sample of strontium-90 to decay to 5.00 grams as the amount gets half.
I believe the answer is "hard water"