Sgr A is believed to be the center of the Milky Way galaxy ...

[Zulu123]

Sgr A is believed to be the center of the Milky Way galaxy because I. it lies in the general direction of the center of the galaxy based on observations of globular clusters in the plane of the Milky Way. II. long-wavelength dust-penetrating images show it to be a region crowded with stars. III. orbits of stars around it indicate a mass several million times that of the Sun within a volume a few light hours in size. IV. radio observations show it is a concentrated source at the center of swirling clouds of gas.
 
  a. I & II only
  b. II & III only
  c. I & IV only
  d. II & IV only
  e. All of I, II, III, & IV

Question 2

The average star spends ________ of its lifetime on the main sequence.
 
  a. 1
  b. 2
  c. 10
  d. 20
  e. 90

[potomatos]

Answer to Question 1

e

Answer to Question 2

e

[Zulu123]

Thank you!

[potomatos]

Always glad to help...