Helium has the smallest atomic radius® Α⇒Ω
It is perpendicular to both as the sidelines are parallel
it is located at the origin so A
hope this helped ^_^
Answer:
The answer to your question is Isotope
Explanation:
Isotopes are atoms with the same number of protons and electrons but their atomic mass is different due to their number of neutrons is different.
In this kind of elements, the number of protons stays the same.
Some isotopes are radioactive but others do not.
Some isotopes are used to know the age of fossils or ancient things.
