Question

question 9 (1 point)
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the correct formulas for chromium(iii)oxide and aluminum phosphate are:

1. cr2o3 and alpo4
2. cr3o2 and al3po4
3. cro and al2(po4)3
4. cr3o3 and al3(po4)2

Explanation:

• For chromium(III) oxide: Chromium has a +3 charge (\(Cr^{3+}\)), and oxide has a -2 charge (\(O^{2 -}\)). Using the criss - cross method (the magnitude of the charge of one ion becomes the subscript of the other), we get \(Cr_{2}O_{3}\).
• For aluminum phosphate: Aluminum has a +3 charge (\(Al^{3+}\)), and phosphate (\(PO_{4}^{3 -}\)) has a -3 charge. Using the criss - cross method (since the magnitudes of the charges are equal), we get \(AlPO_{4}\).

Answer:

1. \(Cr_{2}O_{3}\) and \(AlPO_{4}\)