$n_{C_2H_5OH}=4,6/46=0,1mol$
$a/C_2H_5OH+3O_2\overset{t^o}\to 2CO_2+3H_2O$
$\text{b/Theo pt :}$
$n_{CO_2}=2.n_{C_2H_5OH}=2.0,1=0,2mol⇒m_{CO_2}=0,2.44=8,8g$
$n_{H_2O}=3.n_{C_2H_5OH}=3.0,1=0,3mol⇒m_{H_2O}=0,3.18=5,4g$
$c/C_2H_5OH+O_2\to CH_3COOH+H_2O$
$\text{Theo pt :}$
$n_{CH_3COOH}=n_{C_2H_5OH}=0,1mol$
$⇒m_{CH_3COOH}=0,1.60=6g$