$\text{Bài 7:}$
$C + O_{2}\hspace{0,3cm} \underrightarrow{t^{o}}\hspace{0,3cm} CO_{2}$
$4P + 5O_{2}\hspace{0,3cm} \underrightarrow{t^{o}}\hspace{0,3cm} 2P_{2}O_{5}$
$3Fe + 2O_{2}\hspace{0,3cm} \underrightarrow{t^{o}}\hspace{0,3cm} Fe_{3}O_{4}$
$CH_{4} + 2O_{2}\hspace{0,3cm} \underrightarrow{t^{o}}\hspace{0,3cm} CO_{2} + 2H_{2}O$
$2CO + O_{2}\hspace{0,3cm} \underrightarrow{t^{o}}\hspace{0,3cm} 2CO_{2}$
$2Mg + O_{2}\hspace{0,3cm} \underrightarrow{t^{o}}\hspace{0,3cm} 2MgO$
$\text{Bài 8:}$
$a) S + O_{2}\hspace{0,3cm} \underrightarrow{t^{o}}\hspace{0,3cm} SO_{2}$
$n_{SO_{2}}=\frac{4,48}{22,4}=0,2 (mol)$
$\text{Theo ptpư: }n_{S}=n_{O_{2}}=n_{SO_{2}}=0,2 (mol)$
$\Rightarrow m_{S}=0,2.32=6,4 (g)$
$\Rightarrow V_{O_{2}}=0,2.22,4=4,48 (l)$
$b)\text{Ta có: } V_{KK}=5V_{O_{2}}$
$\Rightarrow V_{KK}=5.4,48=22,4 (l)$