Answer:Atomic model keep changing because the electrons around the nucleus are not fixed and they keeps rotating or changing their position in valence orbits around the nucleus.
Explanation:
My guess would be about 10 years because stars are hot balls of light that are reflections from years ago so it would most likely take awhile
Speed = (frequency)x(wavelength).
Frequency = 6 Hz
Wavelength = 9mm = 0.009m.
Speed = (6 Hz) x (0.009m) = 0.054 m/s or 54 mm/sec.
The apparent magnitude scale is a classification scheme which is based on the brightness of stars. The range of brightness values is from 1 to 6.
The stars which are the most brightest are ranked as number 1 and also called first magnitude stars, stars which are little dimmer than number 1 are ranked as number 2 and also called second magnitude stars. Similarly the most faintest stars are ranked number 6 and also called as the sixth magnitude stars.