When Barium chloride is formed, what questions will the student need to know prior to making the formula???

Valency of the two elements

Explanation:

In order to correctly formularize the compound, the student needs to ask of the valences of the elements involved.

Chlorine has valency of -1, while Barium +2.

The exchange of valency gives the formula .

Another explanation is that Barium donates 2 electrons which the chlorine atoms accept, in order to form the covalent bond.

I hope this was helpful.

it's all four options.