解:设消耗氧气的质量为$y,$生成氧化镁的质量为$z。$
$2\text{Mg}+\text{O}_2\stackrel{\text{点燃}}{=}2\text{MgO}$
48 32 80
24g y z
$\frac{48}{32}=\frac{24\,\text{g}}{y}$
$y=\frac{24\,\text{g}\times32}{48}=16\,\text{g}$
$\frac{48}{80}=\frac{24\,\text{g}}{z}$
$z=\frac{24\,\text{g}\times80}{48}=40\,\text{g}$
答:需消耗氧气$16\,\text{g},$生成氧化镁$40\,\text{g}。$