At STP volume is 22.4 L
Molar mass NO₂ = 46.0 g/mol
1 mole ---------- 22.4 L
? mole ---------- 11.4 L
moles = 11.4 * 1 / 22.4
moles = 11.4 / 22.4
= 0.5089 moles of NO₂
Mass NO₂ :
moles NO₂ * molar mass
0.5089 * 46.0
= 23.4094 g of NO₂
hope this helps!