There is an explosion on the surface of a lake and two person Seema and John hear it's sound. Seema is 150m away on a boat and. John is 150 m below the surface of water. Who would hear the sound first and why?

John would hear the sound first  because sound travels  faster in water than in air

Explanation:

The location of the point of the explosion = On the water surface

The distance between Seema and the sound = 150 m

The medium through which the sound reaches Seema = Through the air

The distance between John and the sound = 150 m

The medium through which the sound reaches John = Through the water

The speed of sound in air = 343 m/s

The speed of sound in water = 1,481 m/s

The time it takes the sound to reach Seema, tₐ = 150 m/(343 m/s) ≈ 0.43732 seconds

The time it takes the sound to reach John, = 150 m/(1,481 m/s) ≈ 0.10128 seconds

The difference in the time it takes sound to reach Seema and John = 0.43732 s - 0.10128 s = 0.33603 s

The sound reaches John approximately 0.33603 seconds before it reaches Seema

Therefore, John would hear the sound first  because sound travels about 4.3 times faster in water than in air.