Bạn tham khảo:
$a/$
$Ca+2H_2O \to Ca(OH)_2+H_2$
$CaO+H_2O \to Ca(OH)_2$
$n_{H_2}=2(mol)$
$n_{Ca}=n_{H_2}=2(mol)$
$b/$
$m_{Ca}=2.40=80(g)$
$m_{CaO}=192-80=112(g)$
$c/$
$n_{CaO}=\frac{112}{56}2(mol)$
$m_{Ca(OH)_2}=4.74=296(g)$
$d/$
$Ca(OH)_2$: Canxi hiđroxit