The correct option is (iii). Two Fe3+ ions provide a total positive charge of 6+ and three O2- ions provide a total negative charge of 6-, making the combination neutral and fully balanced.
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 PO4 3- (iii) 2 Fe3+ and 3 O2- (iv) 3 Ca2+ and 2 SO4 2-
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Option (iii) is the correct answer. In this combination, two ferric ions Fe3+ contribute a positive charge calculated as two multiplied by plus three, totaling plus six. Three oxide ions O2- contribute a negative charge calculated as three multiplied by minus two, totaling minus six. This perfectly satisfies the requirement of having a total 6+ positive charge and 6- negative charge.
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