What is the oxidation number of each phosphorus atom (P) in the compound calcium phosphite, Ca3(PO3)2?

-2
-3
+3
+6

Question

What is the oxidation number of each phosphorus atom (P) in the compound calcium phosphite, Ca3(PO3)2?
 	
	-2
	-3
	+3
	+6

anonymous · Answer

I think it is 3+ but I am not sure

anonymous · Answer

It is + 6!

anonymous · Answer

3(+2)  + 2x - 6(+2) = 0

jfraser · Answer

the calcium ions are actually irrelevant in finding the oxidation state of the elements in the phosphite ion. The $PO_3^{-3}$ ion has 3 oxygen ions in it, each at a -2. The whole ion must have a net charge of -3. The algebra works out to:$$X + 3(-2) = -3$$ The only logical answer is that the phosphorus is a +3