Final answer:
The correct answer to the question of which option correctly represents an ion pair and the ionic compound they form is option a. Ca²⁺, F⁻; CaF₂, where calcium ions pair with fluoride ions to form calcium fluoride.
Step-by-step explanation:
The student is asking which of the following correctly represents an ion pair and the ionic compound the ions form from the given options. To form an ionic compound, the total positive charge must balance the total negative charge. Let's analyze each option:
- a. Ca²⁺, F⁻; CaF₂ - This is correct. Calcium has a 2+ charge and needs two fluoride ions, each with a -1 charge, to balance out and form calcium fluoride, CaF₂.
- b. Na⁺, Cl⁻; NaCl₂ - This is incorrect. A single sodium ion (Na⁺) would pair with a single chloride ion (Cl⁻) to form sodium chloride, NaCl. The subscript '2' is not needed for chlorine since it has a -1 charge and only requires one sodium ion to balance.
- c. Ba²⁺, O²⁻; Ba₂O₂ - This is also incorrect. The correct formula for the ionic compound formed between barium and oxygen would be BaO. Each barium ion with a 2+ charge balances with one oxide ion with a 2- charge.
- d. Pb⁴⁺, O²⁻; Pb₂O₄ - This option is incorrect as well. The correct formula for the ionic compound formed between lead(IV) and oxygen would be PbO₂, where one lead ion with a 4+ charge is balanced by two oxide ions with a 2- charge each.
Thus, the correct answer to the student's question is option a. Ca²⁺, F⁻; CaF₂ as this correctly represents the ion pair and the ionic compound they form.