text: ok herez what i think the answers are.. i've explained with reasons..\n\n\n1) If ur talkin about waves in general then its false because electromagnetic waves can transmit without a medium.. thats how they r transmitted through space..\nBut since most ur questions r related to sound.. I'm assuming ur talkin abt trasmitting sound waves.. then its true.. coz sound waves require a medium\n\n2)false.. sound travels faster through water than through air\n\n3)True... higher temperature means particles have more kinetic energy n thus vibrate faster.. so they pass on the energy at a higher rate.. so sound waves travel faster at higher tempr.. \n\n4)false.. hertz corresponds to frequency.. ie.. the number of waves produced per second.. if ur increasing the frequency, ur producing more waves in the same time.. so the wave length has to be decreased in order to acheive this \nalso, f = v/lambda... frequency and wavelength are inversely proportional to each other..\n\n5) true... Each decibel is one tenth of a bel, which is a unit that measures the intensity of sound.  For every six decibels, the intensity of the sound doubles. \n\n6) True... FM waves are in megahertz while AM are only in kHz ... since E = hf... energy and frequency are directly proportional.. so higher frequency means more energy..