As a star forms, the photosphere first appears: A) when the ...

[Lisaclaire]

As a star forms, the photosphere first appears:
 
  A) when the planetary nebula is expelled.
  B) when the protostar forms.
  C) when contraction slows down.
  D) when nuclear fires ignite.
  E) when the star reaches the main sequence.

Question 2

The particles which enter into chemical reactions are the atom's:
 
  A) protons.
  B) neutrons.
  C) positrons.
  D) electrons.
  E) mesons.

[amandanbreshears]

Answer to Question 1

B

Answer to Question 2

D