\(2KMnO_4\rightarrow K_2MnO_4+MnO_2+O_2\)
a,
\(n_{O2}=\frac{24}{32}=0,75\left(mol\right)\)
\(\rightarrow n_{KMnO_4}=0,75.2=1,5\left(mol\right)\)
\(\Rightarrow m_{KMnO_4}=1,5.\left(39+55+16.4\right)=237\left(g\right)\)
b,
\(n_{O2}=\frac{33,6}{22,4}=1,5\left(mol\right)\)
\(\rightarrow n_{KMnO4}=1,5.2=3\left(mol\right)\)
\(\Rightarrow m_{KMnO4}=3.\left(39+55+16,4\right)=474\left(g\right)\)