In a binary system, the more massive star a. is at the center ...

[michelleunicorn]

In a binary system, the more massive star
 
  a. is at the center of mass.
  b. is farthest from the center of mass.
  c. is nearest the center of mass.
  d. follows the largest orbit.
  e. shows a larger Doppler shift in its spectral lines.

Question 2

A nanometer is
 
  a. a unit of frequency.
  b. a unit of energy.
  c. a unit of mass.
  d. a unit of length.
  e. a unit of resolving power.

[tdewitt]

Answer to Question 1

c

Answer to Question 2

d

[michelleunicorn]

Thanks for the timely response, appreciate it

[Bigfoot1984]

Excellent