2N₂O + 3O₂ ⇒ 4NO₂
mol N₂O = 9 g : 44 g/mol = 0.205
mol O₂ = 3/2 x 0.205 = 0.3075
mass O₂ = 0.3075 x 32 g/mol = 9.84 g
=================================
mol O₂ = 7.5 g : 32 g/mol = 0.234
mol NO₂ (smog) = 4/3 x 0.234 = 0.312
mass NO₂ = 0.312 x 46 g/mol = 14.352 g