Answer:
b) twice the energy of each photon of the red light.
Explanation:
= Wavelength
h = Planck's constant = 
c = Speed of light = 
Energy of a photon is given by

Let
= 700 nm

For red light

For UV light

Dividing the equations

Hence, the answer is b) twice the energy of each photon of the red light.
Possibly, if you have list of densities and you have to match it. I can't think of any other scenarios in which it would be able to.
Hope I helped! :)
The answer to the blank is physical.
Answer:
Sound and light are similar in that both are forms of energy that travel in waves. They both have properties of wavelength, freqency and amplitude. Here are some differences: Sound can only travel through a medium (substance) while light can travel through empty space.
When water evaporates of your body it cools you down, hence why after a shower when the water droplets begin to evaporate you feel cold