The outer planets are small, rocky planets with iron cores. true or false

Simple machines can a. increase force only b. decrease force only c. increase or decrease force

Acompound machine is also called a machine. a. force b. simple c. complex d. directional

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?