Answer:
B and D as well
Explanation:
All the electronic configuration of the elements of B end on s sub shell.
S energy level sub shell can hold 2 electrons and since Be, Mg, Ca Sr end in s.
We can say, they have same valence electrons, i.e 2 electrons.
C
The elements are Lithium and Beryllium— just look at the mass number on the periodic table
The average atomic mass of Sn is 118.71 g/mol
the percentage of heaviest Sn is 5.80%
the given mass of Sn is 82g
The total moles of Sn will be = mass / atomic mass = 82/118.71=0.691
Total atoms of Sn in 82g = 
the percentage of heaviest Sn is 5.80%
So the total atoms of 
= 5.80% X 
Total atoms of =
atoms
the mass of will be = 
Answer: The one listed below that's NOT an example of potential energy is mechanical energy. Mechanical energy is categorized as a kinetic energy with light, sound, and thermal/heat energy.
HOPE THIS HELPS
