Answer:
The index of refraction of the liquid is 1.35.
Explanation:
It is given that,
Critical angle for a certain air-liquid surface, 
Let n₁ is the refractive index of liquid and n₂ is the refractive index of air, n₂ =1
Using Snell's law for air liquid interface as :




So, the index of refraction of the liquid is 1.35. Hence, this is the required solution.
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2. Hitting a tennis ball
3. Swinging a bucket of water in a circle
D. The noise of a car horn. Hope this helps! Please comment if it does!