a) $n_{H_2} = \dfrac{1,12}{22,4} = 0,05(mol)$
$CuO + H_2 \xrightarrow{t^o} Cu + H_2O$
Theo PTHH : $n_{CuO} = n_{H_2} = 0,05(mol)$
$m_{CuO} = 0,05.80 = 40(gam)$
b) $Zn + 2HCl \to ZnCl_2 + H_2$
Theo PTHH : $n_{Zn} = n_{H_2} = 0,05(mol)$
$m_{Zn} = 0,05.65 = 3,25(gam)$