\(\begin{array}{l}
a)\\
CTHH:Cu_xS_yO_z\\
x:y:z=\frac{12,8}{64}:\frac{6,4}{32}:\frac{12,8}{16}=0,2:0,2:0,8=1:1:4\\
\to CTN:(CuSO_4)_n\\
M=160\to (63+32+16.4).n=160\\
\to n=1\to CTHH:CuSO_4\\
b)\\
n_C=n_{CO_2}=\frac{4,48}{22,4}=0,2(mol)\\
n_H=2n_{H_2O}=2.\frac{3,6}{18}=0,4(mol)\\
TH_1:\,A\,gom\,C,H,O\\
\to A:C_xH_yO_z\\
\to x:y=0,2:0,4=1:2\\
\to A:C_nH_{2n}O_z\\
\to 12n+2n+16z=14.2=28\\
\to 14n+16z=28(\rm vô\,nghiệm\,nguyên\,dương)\\
TH_2:\,A\,gom\,C,H\\
\to n_C:n_H=0,2:0,4=1:2\\
\to CTN:(CH_2)_n\\
M=14.2=28\\
\to (12+2).n=28\\
\to n=2\\
\to CTHH:C_2H_4
\end{array}\)