\(\Rightarrow i=\sin ^{-1}\left(\frac{1}{\mu}\right)\)

\(\Rightarrow i=45^{\circ}\)

\(\text { and according to snell's law }\)

\(1 \sin 45^{\circ}=\sqrt{2} \sin r\)

\(\Rightarrow \mathrm{r}=30^{\circ}\)

\(\text { Lateral displacement } \Delta=\frac{\mathrm{t} \sin (\mathrm{i}-\mathrm{r})}{\cos \mathrm{r}}\)

\(\Rightarrow \Delta=\frac{4 \sqrt{3} \times \sin 15^{\circ}}{\cos 30^{\circ}}\)

\(\Rightarrow \Delta=2 \mathrm{~cm}\)