Balancing charges in ionic compounds

Steps:

• Identify charges: Ca²⁺ has +2 charge, PO₄³⁻ has -3 charge.
• Find least common multiple of 2 and 3, which is 6, to balance total charge.
• Use 3 Ca²⁺ ions for +6 charge (3 × +2 = +6).
• Use 2 PO₄³⁻ ions for -6 charge (2 × -3 = -6).
• Write formula as Ca₃(PO₄)₂, with subscripts indicating ratio.

Why A is correct:

• Ca₃(PO₄)₂ achieves charge neutrality with the lowest whole-number ratio, following the rule for ionic compound formulas.

Why the others are wrong:

• B: Ca(PO₄) gives +2 and -3, unbalanced charges.
• C: Ca₃PO₄ gives +6 and -3, unbalanced charges.
• D: Ca₃(PO₄) gives +6 and -3, unbalanced charges.

Final answer: A