\(\begin{array}{l}
C + {O_2} \to C{O_2}\\
nC = \dfrac{{96}}{{12}} = 8\,mol\\
 =  > n{O_2} = 8mol\\
V{O_2} = 8 \times 22,4 = 179,2l\\
m{O_2} = 8 \times 32 = 256g\\
4P + 5{O_2} \to 2{P_2}{O_5}\\
nP = \dfrac{{7,75}}{{31}} = 0,25\,mol\\
 =  > n{O_2} = 0,3125\,mol\\
V{O_2} = 0,3125 \times 22,4 = 7l\\
m{O_2} = 0,3125 \times 32 = 10g
\end{array}\)

$n_C=96/12=8mol$

$n_P=7,75/31=0,25mol$

$C+O_2\overset{t^o}{\rightarrow}CO_2$

$8→8$

$⇒V_{O_2}=8.22,4=179,2l$

$m_{O_2}=8.32=256g$

$4P  +  5O_2\overset{t^o}{\rightarrow}2P_2O_5$

$0,25→0,3125$

$⇒V_{O_2}=0,3125.22,4=7l$

$m_{O_2}=0,3125.32=10g$