$1)n_{H_2}=0,03 mol\Rightarrow n_{Na}=0,06 mol$$\Rightarrow n_{CO_2}=\frac{4,032}{22,4}-n_{Na_2CO_3}=0,18-0,03=0,15 mol$
$2)$
$2C_\overline{n}H_{2\overline{n}+1}COONa \overset{+O_2}{\rightarrow}(2\overline{n}+1)CO_2+(2\overline{n}+1)H_2O+Na_2CO_3$
$2x (2\overline{n}+1)x (2\overline{n} +1)x x$
$\Rightarrow \begin{cases}x=\frac{2,65}{106} \\ (44-18)(2\overline{n}+1)x=3,51 \end{cases}\Rightarrow \begin{cases}x=0,025 mol \\ \overline{n} =2,2 \end{cases}$
Coi $X:\begin{cases}HCOONa:0,01 mol \\ C_nH_{2n+1}COONa:(2.0,025-0,01) mol \end{cases}$
$\Rightarrow \frac{0,01.0+0,04.n}{0,05}=2,2\Rightarrow n=2,75\Rightarrow X:\begin{cases}HCOONa \\ C_2H_5COONa\\C_3H_7COONA \end{cases}$