The size of a galaxy's central black hole is proportional to the mass of its disk.
a. True
b. False
Indicate whether the statement is true or false
Question 2
An atom must emit a photon when a(n) ____.
a. electron moves from a lower to a higher energy level
b. proton moves from a lower to a higher energy level
c. proton moves from a higher to a lower energy level
d. electron moves from a higher to a lower energy level
e. atom becomes ionized
