No. The speed of light does change. You mean speed of light in a vacuum. Measuring that value is elementary, in a 2-way measurement, as you show.
The answer is silicon because it’s atomic number is 14
Geologists use these records to establish the structure of Earth's interior. The two principal types of seismic waves are P-waves (pressure; goes through liquid and solid) and S-waves (shear or secondary; goes only through solid - not through liquid).
Because the atom isn't a isotope. The electrons, (negative charge) , and the protons, (positive charge), balance each other out.
A solid to a liquid, the boiling of water, solid the water molecules vibrate condensed but as a liquid they are still isolated in a controlled area and also reflect off one another more, liquid to a gas they do not and move freely until condensation occurs
