a$)$ Find the volume of the solid generated by rotating the region, bounded by $y=x,y=2$ and $x=0,$ about

i$)x-$ axis

ii$),y-$ axis

b$)$ Find the volume of the solid generated by rotating the region, bounded by $x=y^2$ and $y=x,$ about i$),x-$ axis

ii$)y-$axis