The result of multiplying the frequency of an oscillating body by its periodic time equals A-1/2 B-1/4 C-1/3 D-1

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?

The electronic structure or chlorine is 2.8.7 what is the electronic structure of fluorine?

How many neutrons does plutonium -196 with an atomic number of 78.