$n_{Zn}=48,6/65≈0,75mol$
$a/2Zn+O_2\overset{t^o}\to 2ZnO$
b/Theo pt :
$n_{O_2}=1/2.n_{Zn}=1/2.0,75=0,375mol$
$⇒V_{O_2}=0,375.22,4=8,4l$
$c/2KClO_3\overset{t^o}\to 2KCl+3O_2$
Theo pt :
$n_{KClO_3}=2/3.n_{O_2}=2/3.0,375=0,25mol$
$⇒m_{KClO_3}=0,25.122,5=30,625g$