Answer is: maximum amount of oxygen is 17,6 g.
Chemical reaction: 4C₃H₅N₃O₉ → 6N₂ +12CO₂ + 10H₂O + O₂.
m(C₃H₅N₃O₉) = 5,00·10² g = 500 g.
n(C₃H₅N₃O₉) = m(C₃H₅N₃O₉) ÷ M(C₃H₅N₃O₉).
n(C₃H₅N₃O₉) = 500 g ÷ 227,09 g/mol.
n(C₃H₅N₃O₉) = 2,2 mol.
From chemical reaction: n(C₃H₅N₃O₉) : n(O₂) = 4 : 1.
n(O₂) = 2,2 mol ÷ 4.
n(O₂) = 0,55 mol.
m(O₂) = n(O₂) · M(O₂).
m(O₂) = 0,55 mol · 32 g/mol.
m(O₂) = 17,6 g.