Total Internal Reflection question from MHT CET 2024 (15 May, Shift 1)

Answer: (a)

1. TIR needs light going from denser to rarer, so (b) and (d) are ruled out.
2. $\sin C = \frac{\mu_{rarer}}{\mu_{denser}}$; $C$ is smallest when this ratio is smallest.
3. Glass to air: $\frac{1}{1.5} = 0.67$; glass to water: $\frac{1.33}{1.5} = 0.89$.
4. So the answer is (a) glass to air.