Venus and Mars probably evolved differently from Earth because: ...

[tth]

Venus and Mars probably evolved differently from Earth because:
 
  A) they are slightly bigger than Earth.
  B) they are more massive than Earth.
  C) they have thicker atmospheres than the Earth.
  D) they formed sooner than Earth.
  E) they orbit at different distances from the Sun.

Question 2

Define emission lines.
 
  What will be an ideal response?

[lcapri7]

Answer to Question 1

E

Answer to Question 2

A hot, thin gas cools off by emitting photons, but only at discrete wavelengths determined by the electron transitions downward of the component atoms. These appear as a pattern of bright emission lines, such as from M-42 in Orion.

[tth]

Excellent

[amcvicar]

Great answer, keep it coming