$2C_\overline{n} H_{2\overline{n} +3}N+(3\overline{n} +1,5)O_2\rightarrow 2\overline{n} CO_2+(2\overline{n} +3)H_2O+N_2$ $x (1,5\overline{n} x+0,75x) \overline{n} x$
$C_mH_{2m}+1,5mO_2\rightarrow mCO_2+mH_2O$
$y 1,5my my$
$\Rightarrow \begin{cases}(1,5\overline{n}x+0,75x)+1,5my=0,2025 mol \\\overline{n}x+my =0,1\end{cases}\Rightarrow \begin{cases}x=0,07 mol \\ 0,07 \overline{n}+my =0,1 \end{cases}$
$0,07\overline{n}<0,1\Rightarrow \overline{n}<1,42\Rightarrow Y:C_2H_5NH_2 $