Explanation
(m) is measured in kilograms (kg)
<h2>(F) is measured in newtons (N)</h2>
<h3>acceleration (a) is measured in metres per second squared (m/s²)</h3>
The Sun is a star around which our planet Earth and other planets and satellites of our solar system revolve along specific orbits. Sun appears to be spherical in shape and consists of glowing hot gases. It contains mostly hydrogen and helium gases. The temperature of the gas mixture is extremely high.
Therefore, the Sun mostly composed of hydrogen and helium gases.
(Answer) B. Composition mostly hydrogen and helium gas, Mass 1.989 x 10^30 Kg
B. Frequency remains unchanged because the energy in a photon is E=hf. So if the frequency changes so does the energy and that doesn't happen to EM waves entering a medium by the conservation of energy