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.
Answer:
1, 1, 2, 3
Explanation:
The numbers 1 and 8 both have 1 sig. fig.
The number 13 has 2 sig. figs.
The number 104 has 3 sig. figs.
