Question

To form oxide ion oxygen atom has to gain:
A.$1$ electron
B.$2$electron
C.$3$electron
D.$4$electron

Answer 1

Oxygen is the chemical element with the symbol $O$ and atomic number eight. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. It has six electrons in its outer shell. It gains two electrons from one or two other atoms in reactions, forming an oxide ion.

Complete answer:
Oxygen has an electron arrangement of $2,6$ and needs to gain two electrons to fill the $n = 2$ energy level and achieve an octet of electrons in the outermost shell. The oxide ion will have a charge of $- 2$ as a result of gaining two electrons. It means that it needs to gain two electrons to obey the octet rule and have a full outer shell of eight electrons. It gains two electrons from other atoms in reactions and forms an oxide ion. The element oxygen has six valence electrons.
Oxygen requires two electrons in its outermost shell, these two electrons are known as valence electrons. Therefore, valence electrons of oxygen are two and it requires two electrons oxide ions.
So the correct answer is (B) $2$electron.

Note:
Oxygen is a colorless, odorless, tasteless gas. It changes from a gas to a liquid at a temperature of $- {182.96^ \circ }C$. The liquid formed has a slightly bluish color to it. Liquid oxygen can then be solidified or frozen at a temperature of $- {218.4^ \circ }C$.