\(n_{CO_2}=\dfrac{1.76}{44}=0.04\left(mol\right)\Rightarrow n_C=0.04\left(mol\right)\)
\(n_{H_2O}=\dfrac{0.72}{18}=0.04\left(mol\right)\Rightarrow n_H=0.04\cdot2=0.08\left(mol\right)\)
\(m_O=0.88-0.04\cdot12-0.08=0.32\left(g\right)\)
\(n_O=\dfrac{0.32}{16}=0.02\left(mol\right)\)
\(TC:\)
\(n_C:n_H:n_O=0.04:0.08:0.02=2:4:1\)
\(CT:\left(C_2H_4O\right)_n\)
\(M_Y=3.04\cdot29=88\left(\dfrac{g}{mol}\right)\)
\(\Leftrightarrow44n=88\)
\(\Leftrightarrow n=2\)
\(CT:C_4H_8O_2\)