$n_{Fe}=2,8/56=0,05mol$
$a/$
$Fe+2HCl→FeCl_2+H_2$
$b/$
$\text{Theo pt :}$
$n_{HCl}=2.n_{Fe}=2.0,05=0,1mol$
$⇒m_{HCl}=0,1.36,5=3,65g$
$c/$
$\text{Theo pt :}$
$n_{H_2}=n_{Fe}=0,05mol$
$⇒V_{H_2}=0,05.22,4=1,12l$
$d/$
$H_2+CuO→Cu+H_2O$
$d1/$
$\text{Theo pt :}$
$n_{CuO}=n_{H_2}=0,05mol$
$⇒m_{CuO}=0,05.80=4g$
$d2/$
$\text{Theo pt :}$
$n_{Cu}=n_{H_2}=0,05mol$
$⇒m_{Cu}=0,05.64=3,2g$