3 ms·

yeah, the speed of sound in mercury is not that slow. Never trust anything you hear on youtube. https://www.engineeringtoolbox.com/sound-speed-liquids-d_715.ht

• majewsky 8y ago
  It makes intuitive sense, too. For sound to travel through a medium, the constituent particles have to interact with their neighbors to keep the sound wave moving. In a liquid, the particles are much closer to their neighbors (on average) than in a gas at normal pressures. Because of this stronger coupling, the average liquid (or solid) should have a much higher speed of sound than the average gas.