What your question for number 3
A polyatomic ion.
Examples: Sulfate, Sulfite, Nitrate, Nitrite...
Answer:
Gravity always pulls objects such as a desk, book or person down. Thus, when you jump gravity causes you to land on the ground. Friction, however, doesn't pull objects down
Answer:
C
Explanation:
For sodium to bond with chlorine, it is through electrovalent bonding.
It means , one electron is transferred from the sodium to the chlorine.
Normally, chlorine has 17 electrons, by adding one , we get 18 electrons.
This is the number of electrons for Argon