. What is the oxidation number of phosphorous in AlPO4?+3+5+2-2

The oxidation number of phosphorous in AlPO4 is +5. Here's how you can determine this:

1. The oxidation number of Aluminium (Al) is +3. This is a rule because Aluminium is a group III element and therefore it has +3 charge.

2. The oxidation number of Oxygen (O) is -2. This is also a rule because Oxygen almost always has an oxidation number of -2.

3. In AlPO4, there are four Oxygen atoms, so the total oxidation number for Oxygen is 4*(-2) = -8.

4. The compound AlPO4 is neutral, so the sum of the oxidation numbers of all atoms in it should be zero.

5. Let's denote the oxidation number of Phosphorous (P) as x. So, we have the equation: +3 (for Al) + x (for P) - 8 (for 4 O atoms) = 0.

6. Solving this equation for x gives: x = +5.

So, the oxidation number of Phosphorous in AlPO4 is +5.