a)\(2KMnO4-->K2MnO4+MnO2+O2\)
\(n_{KMnO4}=\frac{94,8}{158}=0,6\left(mol\right)\)
\(n_{O2}=\frac{1}{2}n_{KMnO4}=0,3\left(mol\right)\)
\(V_{O2}=0,3.22,4=6,72\left(l\right)\)
c) \(2Zn+O2-->2ZnO\)
\(n_{ZnO}=2n_{O2}=0,6\left(mol\right)\)
\(m_{ZnO}=0,6.81=48,6\left(g\right)\)