It's basically a wave that moves back and forth at regular speed through matter. because of that it transfers energy through a medium (matter). however the movement of the wave is limited because of this but it can still move over long distances. so because of this these types of waves don't move far from their original point or Equilibrium position. in short think of throwing a pebble into water and seeing the little ripples from it, that's a mechanical wave.
The aqueous bromothymol blue solution act as a pH indicator and turns blue only in case when the pH of the sample is above or equal to 7.6
Since the pH of the water at the surface of the lakes is higher and ranges between 7.5 to 8.5 the color of bromothymol turn blue.
They are both living this and they are both made of cells
A hot dog would work but you didn't hear