What is the most electrons that a shell can contain?

1400 kg car has a speed of 27 m/s. if it takes 7 s to stop the car, what is the impulse and the average force acting on the car?

What is the magnitude of the resultant vector round your answer to the nearest tenth

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?