Survival of the fittest they are able to mature and reproduce because of their advantageous qualities
If the wavelength increases (gets longer), then the frequency <em>decreases</em>.
(A wave occurs less often.)
When you add heat to a substance, it disrupts their molecular bonding, causing them to vibrate quicker and increasing the space between each molecule.
Velocity and a speed is the reason for the weight of it as well i actually have no idea