Question

Why is speed of sound faster in sea water than distilled water?

Answer 1

Bcoz density of distilled water is more than that of sea water and speed of sound is inversely proportional to density. Hence sea water has more speed of sound in it than distilled water

Answer 2

sea water contains minerals and dissociated ions like Mg2+ , Na+ , Cl- which will form an electrolyte as the sound . 

also Speed of sound in any medium depends on the density of the medium As sound wave is propagated due to vibration of particles, closer the particles / denser the particles faster the speed of sound.