Quasars are common in the early Universe because ____ at that time.
a. galactic collisions were more frequent
b. black hole collisions were more frequent
c. gas and dust clouds were denser
d. galaxies were more isolated
e. central bulges were larger
Question 2
A(n) _______________ is an atom that has gained or lost one or more electrons.
Fill in the blank(s) with correct word