\(a.\)
\(n_C=\dfrac{9.6}{12}=0.8\left(mol\right)\)
\(n_{O_2}=\dfrac{1.12}{22.4}=0.05\left(mol\right)\)
\(C+O_2\underrightarrow{^{t^0}}CO_2\)
\(0.05...0.05..0.05\)
\(\Rightarrow Cdư\)
\(V_{CO_2}=0.05\cdot22.4=1.12\left(l\right)\)
\(b.\)
\(n_P=\dfrac{6.2}{31}=0.2\left(mol\right)\)
\(n_{O_2}=\dfrac{1.12}{22.4}=0.05\left(mol\right)\)
\(4P+5O_2\underrightarrow{^{t^0}}2P_2O_5\)
\(0.04....0.05......0.02\)
\(\Rightarrow Pdư\)
\(m_{P_2O_5}=0.02\cdot142=2.84\left(g\right)\)