Final answer:
The chemical formulas for compounds formed from pairs of ions are BaS, Li₂O, Ca₃N₂, and CuI₂.
Step-by-step explanation:
In order to write the chemical formulas for compounds formed from pairs of ions, we need to balance the charges of the ions. The charges of the ions give us the ratio of the ions in the compound. Here are the chemical formulas for the given pairs of ions:
A) Ba²⁺, S²⁻: The charges on the ions are balanced, so the formula is BaS.
B) Li⁺, O²⁻: The charges on the ions are balanced, so the formula is Li₂O.
C) Ca²⁺, N³⁻: To balance the charges, we need three Ca²⁺ ions and two N³⁻ ions. So the formula is Ca₃N₂.
D) Cu²⁺, I⁻: The charges on the ions are balanced, so the formula is CuI₂.