PTHH: \(Mg+\dfrac{1}{2}O_2\xrightarrow[]{t^o}MgO\)
Ta có: \(n_{Mg}=\dfrac{4,8}{24}=0,2\left(mol\right)\)
\(\Rightarrow\left\{{}\begin{matrix}n_{O_2}=0,1\left(mol\right)\\n_{MgO}=0,2\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}V_{O_2}=0,1\cdot22,4=2,24\left(l\right)\\m_{MgO}=0,2\cdot40=8\left(g\right)\end{matrix}\right.\)