$a.PTHH : \\2Cu+O_2\overset{t^o}\to 2CuO(1) \\b.n_{CuO}=\dfrac{19,2}{80}=0,24mol \\Theo\ pt\ (1) : \\n_{O_2}=\dfrac{1}{2}.n_{CuO}=\dfrac{1}{2}.0,24=0,12mol \\⇒V_{O_2}=0,12.22,4=2,688l \\c. PTHH : \\2KMnO_2\overset{t^o}\to K_2MnO_4+MnO_2+O_2(2) \\Theo\ pt\ (2) : \\n_{KMnO_4}=2.n_{O_2}=2.0,12=0,24mol \\⇒m_{KMnO_4}=0,24.158=37,92g$