Electromagnetic waves all move at the same wave speed. which of these offer solutions to slowing them down select all that apply

how are the waves travel through the water

have the waves move through the air

have the waves move through the vacuum of space

The atoms in a nickel crystal vibrate as harmonic oscillators with an angular frequency of 2.3 × 1013 rad/s. the mass of a nickel atom is 9.75 × 10-26 kg. what is the difference in energy between adjacent vibrational energy levels of nickel? (h = 6.626 × 10-34 j • s, , 1 ev = 1.60 × 10-19 j)