You can tell by how many of the smallest increments there are and the first big number. in this case for number 1 each increment would be worth 1, because it reaches ten and has ten increments. While the one next to it would be worth 2.5, because 10 divided by four equals 2.5. Hope this helps!
Answer:
Krypton
Explanation:
When Selenium forms an ion, it is trying to become krypton which is a noble gas.
Selenium belongs to the oxygen group on the periodic table. In this group, the atoms prefers to gain two electrons to complete their octet. When selenium gains two electrons, its octet is complete.
This will make the atom resemble krypton on the periodic table of elements.
This structure which is an octet confers a special stability on the element.
