$n_{Zn}=19,5/65=0,3mol$
$2Zn+O_2\overset{t^o}\to 2ZnO$
a/
Theo pt :
$n_{O_2}=1/2.n_{Zn}=0,15mol$
$⇒V_{O_2}=0,15.22,4=3,36l$
$⇒V_{kk}=3,36.5=16,8l$
b/
$2KClO_3\overset{t^o}\to 2KCl+3O_2$
Theo pt :
$n_{KClO_3}=2/3.n_{O_2}=2/3.0,15=0,1mol$
$⇒m_{KClO_3}=0,1.122,5=12,25g$