In figure, light is incident at an angle $\mathrm{\theta }$ which is slightly greater than the critical angle. Now, keeping the incident angle fixed a parallel slab of refractive index n₃ is placed on surface AB. Which of the following statements are correct?

(1) $\to {\mathrm{n}}_3<{\mathrm{n}}_1$ so critical angle decreases. Therefore, TIR will take place at AB.

(2) $\to {\mathrm{n}}_3>{\mathrm{n}}_1$, so critical angle increases. Therefore, TIR will not take place.

(3) $\to \mathrm{If} {\mathrm{n}}_3>{\mathrm{n}}_2$, then TIR will take place at CD and if ${\mathrm{n}}_3>{\mathrm{n}}_1$, then TIR will take place at AB.

(4) $\to$ TIR will not take place at face CD for ${\mathrm{n}}_3<{\mathrm{n}}_1$ because ray is going from rarer to denser medium.