Characteristics of a medium wave. They are <span>Wavelengths in this band are long enough that radio waves are not blocked by buildings and hills and can propagate beyond the horizon following the curvature of the Earth; this is called the </span>ground wave<span>. Practical groundwave reception typically extends to 200–300 miles, with longer distances over terrain with higher </span>ground conductivity<span>, and greatest distances over salt water. Most broadcast stations use ground wave to cover their listening area. Hope this helps. :)</span>
Resources found in lithosphere: gold and iron etc
Resources found in atmosphere: Water vapor, gases etc.
Because they're not confident enough to confirm it's indeed true but they will support it for they believe it's correct.
Frequency = speed of light/ wavelength of photon. wavelength = speed of light/frequency = 3 x 10^8 / 2.43 x 10^8= 1.23m