In Bohr’s model, the lowest energy level is called the ground state. The principal quantum number "n" equals 1 for this state. A. The ground state is unstable. The electron eventually spirals into the nucleus, just like in the solar system model. B. The ground state is stable. If no photons are directed at the atom, the electron will just stay in the n=1 orbit. C. The ground state is stable. However, the electron occasionally moves closer to the nucleus, but it quickly returns to n=1

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?