\(a.M_{C_2H_6O}=12,2+2+16=46\left(đvC\right)\\ \%C=\dfrac{12.2}{46}.100=52,17\%\\ \%H=\dfrac{6}{46}.100=13,04\%\\ \%O=100-52,17-13,04=34,79\%\\ b.n_{CO_2}=\dfrac{6.6}{44}=0,15\left(mol\right)\\ BTNT\left(C\right):n_{C_2H_6O}.2=n_{CO_2}.1\\ \Rightarrow n_{C_2H_6O}=0,075\left(mol\right)\\ \Rightarrow m_{C_2H_6O}=0,075.46=3,45\left(g\right)\)