Question

for what angle of incidence , the lateral siaplcement is maximum ? can it be zero

Answer 1

The formula for lateral displacement (x) is given by :
x = $\frac{t\sin (i_1-r_1)}{\cos r_1}$
where t is the thickness of glass slab, i₁ is angle of incidence of light on the surface of glass slab and r₁ is the angle of refraction corresponding to angle of incidence in glass slab.
Lateral displacement (x) will be maximum when ​ i₁ = 90⁰.
Yes, it can be zero for zero angle of incidence.