Here's how to determine the number of electrons transferred to form aluminum oxalate:

1. Identify the Ions

* Aluminum (Al) forms a +3 ion (Al³⁺).

* Oxalate (C₂O₄) forms a -2 ion (C₂O₄²⁻).

2. Determine the Formula

To balance the charges, we need two aluminum ions (2 x +3 = +6) and three oxalate ions (3 x -2 = -6). The formula for aluminum oxalate is Al₂(C₂O₄)₃.

3. Calculate Electron Transfer

* Each aluminum atom loses 3 electrons to become Al³⁺.

* Each oxalate ion gains 2 electrons to become C₂O₄²⁻.

Since we have two aluminum ions and three oxalate ions:

* Total electrons lost: 2 Al ions * 3 electrons/ion = 6 electrons

* Total electrons gained: 3 C₂O₄²⁻ ions * 2 electrons/ion = 6 electrons

Therefore, a total of 6 electrons must be transferred to form one formula unit of aluminum oxalate.