This is the third most abundant gas in the atmosphere this is from a crossword puzzle and it has 5 letters.

What is the scientific definition of energy that relates to work

Modern physics a photon emitted from an excited hydrogen atom has an energy of 3.02 electron volts. which electron energy-level transition would produce this photon? a. n=1 to n=6 b. n=2 to n=6 c. n=6 to n=1 d. n=6 to n=2 i chose b but the correct answer is d can someone tell me why? and what's the difference?

What are similarities and differences of reflection, refraction, diffraction and absorption?