So half life is the time taken for a sample to decay to half its original mass, its a constant and applies to any original mass, it could be 5g or 1kg, it will take the same amount of time for the original mass to half. In this case the half life is 3 days.
After 3 days the sample will be at half its original mass, now 50g.
Now we can treat the 50g as if its a new sample. After another 3 days (6 days in total) there will be half of 50g left, = 25g.
Answer:
Se =[Ar] 3d¹⁰ 4s² 4p⁴
Explanation:
The noble gas notation is used for the shortest electronic configuration of other periodic table elements.
For example:
The atomic number of Argon is 18, and its electronic configuration is,
Ar₁₈ = 1s² 2s² 2p⁶ 3s² 3p⁶
The atomic number of selenium is 34, its electronic configuration is,
Se₃₄ = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁴
By using the noble gas notation, electronic configuration of selenium can be written is shortest form.
Se =[Ar] 3d¹⁰ 4s² 4p⁴
This electronic configuration is also called abbreviated electronic configuration.
I am sure, the answer is variant B.
