Answer:
b) Phosphorus acid
Explanation:
To distinguish the type of acid of phosphorus with the oxidation state of +3, we need to be familiar with the chemical formula of each of the compounds:
Orthophosphoric acid H₃PO₄
Phosphorus acid H₃PO₃
Metaphosphoric acid HPO₃
Phyrophosphoric acid H₄P₂O₇
Now that we know the formula of the given compounds, the algebraic sum of all the oxidation numbers of all atoms in a neutral compound is zero:
Only phosphorus acid yielded an oxidation state of +3 for phosphorus in the compound.
H₃PO₃:
we know the oxidation state of H = +1
O = -2
The oxidation state of P is unknown. We can express this as an equation:
3(+1) + P + 3(-2) = 0
3 + P -6 = 0
P-3 = 0
P = +3
