The major impact in the Yucatan wiped out the dinosaurs: A) ...

[rachel9]

The major impact in the Yucatan wiped out the dinosaurs:
 
  A) about 450 million years ago.
  B) about 200 million years ago.
  C) about 65 million years ago.
  D) about 36 million years ago.
  E) less than 2 million years ago.

Question 2

What do we mean by the term molecular clouds? Why do they exist? How can observation of their properties yield clues to the processes of stellar formation?
 
  What will be an ideal response?

[sylvia]

Answer to Question 1

C

Answer to Question 2

Molecular clouds are very cool interstellar gas clouds, cool enough that complex molecules can form. A shock wave, from an emission nebula or an exploding star, can lead to star formation in the molecular cloud.

[rachel9]

Excellent

[amandanbreshears]

Thanks for the timely response, appreciate it