The second one is the way to go.
Answer:
oxygen
Explanation:
because the 2nd shell is not complete which is suppose to be 8 and since oxygen is 8 it first shell is 2 which is complete and the second shell which is 6 is not complete because we all know that 2+6=8 but the standard shell is
K-2
L-8
M-8
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.
Depending on the type of pea, the peas should come to the top as they are lighter and larger. Then just scoop or brush them off into another container. If you separate it into smaller batches and work them one by one, you should then find you get pure rice batches left which you can put in their own container.
Its two elements put together