The mystery of matter part 1 out of thin air

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?

Who was the first scientist to measure speed as distance over time?

Which body part transports oxygen removes waste materials in carries nutrients to the body as part of the circulatory system