You are here
You want to design a new ionic compound, where the total positive charge is 6+ and the total negative charge is 6−. Which of the following combinations gives the correct number of ions? (i) 2 Al³⁺ and 3 Cl⁻ (ii) 3 Mg²⁺ and 1 PO₄³⁻ (iii) 2 Fe³⁺ and 3 O²⁻ (iv) 3 Ca²⁺ and 2 SO₄²⁻
View Answer
- (i) 2 Al³⁺ = 6+ but 3 Cl⁻ = 3− — not balanced.
- (ii) 3 Mg²⁺ = 6+ and 1 PO₄³⁻ = 3− — not balanced.
- (iii) 2 Fe³⁺ = 6+ and 3 O²⁻ = 6− — correct (Fe₂O₃).
- (iv) 3 Ca²⁺ = 6+ and 2 SO₄²⁻ = 4− — not balanced.
Answer: (iii)
