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.
It is 20 because then you will put 30 inside of 20milimeeter and put 70 years into the other pint and put it learnt into the cup
Answer:
C₁₆H₃₂O₂ (s) + 22O₂(g) → 16CO₂(g) + 16H₂O(g)
Explanation:
In order to determine a combustion reaction we should know that:
Reactants are: X compound and O₂
Products are: CO₂ and H₂O
In this case, the X compound is the solid palmitic acid: C₁₆H₃₂O₂
The balanced equation will be:
C₁₆H₃₂O₂ (s) + 22O₂(g) → 16CO₂(g) + 16H₂O(g)