Answer:
-2 oxide ion
c) the positive ion
Explanation:
1) Oxygen is present in group six-A. It has six number of valance electrons. It gain two electrons from other element and complete the octet.
When it gain the electron negative charge is created on oxygen thus it form -2 oxide ion.
2) The barium in BaCl₂ is written first because it is cation.
Barium chloride is formed by the reaction of barium and chlorine.
Ba + Cl₂ → BaCl₂
Barium is alkaline earth metal. it has two valance electrons. When it combine with halogen it required two halogen atoms to donate its two valance electron and thus get stable. The charge on barium is +2 and halogen atom is -1 when two halogen atoms combine with it charge becomes -2 and over all compound becomes neutral.
When the formula of compound is written cation are usually written first and anion are written second.
