Why P2O5 does not show oxidising properties while N2O5 is the strongest oxidising agent among pnictogen oxides? Stability of oxides of higher oxidation state decreases with increasing atomic number
Then why P2O5 is thermally stable while N2O5 not.
Infact N2O5 is the strongest oxidising agent among pnictogen oxides because N2O3 is most stable.
Please Offer a lucid explaination to understand this...
A very easy half-answer would base this on electronegativity.

Nitrogen’s electronegativity is $\approx 3$ while phosphorus’ is $2.19$. Oxygen’s is, of course, $3.5$. So the electronegativity difference between nitrogen and oxygen is much lower, meaning that oxygen is much less able to stabilise nitrogen’s high oxidation state.

Contrarily, phosphorus’ low electronegativity means oxygen can stabilise its high oxidation state rather well and the compound is much less likely to act as an oxidating agent by itself.