\(PTHH:Fe+6HNO_{3\left(đặc,nóng\right)}\rightarrow Fe\left(NO_3\right)_3+3NO_2\uparrow+3H_2O\\ n_{Fe}=\dfrac{14}{56}=0,25\left(mol\right)\\ \Rightarrow n_{NO_2}=3n_{Fe}=0,75\left(mol\right)\\ \Rightarrow V_{NO_2\left(đktc\right)}=0,75\cdot22,4=16,8\left(l\right)\)