\(\begin{array}{l}
2)\\
a)\\
CTHH:N{a_x}{H_y}{C_z}{O_t}\\
x:y:z:t = \frac{{27,38}}{{23}}:\frac{{1,19}}{1}:\frac{{14,29}}{{12}}:\frac{{57,14}}{{16}} = 1:1:1:3\\
 =  > CTHH:NaHC{O_3}\\
b)\\
CTHH:{C_x}{H_y}\\
x:y = \frac{{85,71}}{{12}}:\frac{{14,29}}{1} = 1:2\\
 =  > CTDGN:C{H_2}\\
MA = \frac{{1,25}}{{\frac{1}{{22,4}}}} = 28g/mol\\
14n = 28 =  > n = 2\\
 =  > CTHH:{C_2}{H_4}\\
3)\\
a)\\
3Fe + 2{O_2} \to F{e_3}{O_4}\\
4Al + 3{O_2} \to 2A{l_2}{O_3}\\
Fe(a\,mol),Al(b\,mol)\\
56a + 27b = 22,2\\
\frac{{232 \times a}}{3} + 51b = 33,4\\
 =  > a = 0,3b = 0,2\\
mAl = 0,2 \times 27 = 5,4g\\
mFe = 0,3 \times 56 = 16,8g\\
b)\\
nF{e_3}{O_4} = 0,1\,mol\\
nA{l_2}{O_3} = 0,1\,mol\\
\% mF{e_3}{O_4} = \frac{{0,1 \times 232}}{{0,1 \times 232 + 0,1 \times 102}} \times 100\%  = 69,46\% \\
\% mA{l_2}{O_3} = 100 - 69,46 = 30,54\% 
\end{array}\)