How many moons does Mars have? A) none B) one C) two D) ...

[NguyenJ]

How many moons does Mars have?
 
  A) none
  B) one
  C) two
  D) three
  E) four

Question 2

How are we able to determine the chemical composition and temperature of any visible object?
 
  What will be an ideal response?

[akemokai]

Answer to Question 1

C

Answer to Question 2

When an electron moves from one energy level to another (makes a transition) in an atom of a given element, it produces a photon of light at a wavelength that is unique to that transition for that element. If this spectral line with this wavelength is observed then, we know that it must have been produced by that element. Which transitions occur are determined largely by the temperature of the gas; for instance, hydrogen shows up best at 10,000 K, while helium lines require even higher temperatures.

[NguyenJ]

Thanks

[akemokai]

Welcome