Question

1. Which of the following are steps in the process of determining which elements are present in stars? (Select all that apply.)

   		Plot the spectra of stars and measure the wavelengths at which absorption lines occur.
   		Collect a sample of gas from a star.
   		Match features in the spectra to known atomic lines of different elements.
   		Identify the wavelength with the maximum intensity in the star's spectrum.

2. Which of the following statements best completes the sentence:

   "When an atom absorbs a photon..."

   		...the photon will be stored in one of the electron's energy levels.
   		...an electron in that atom will move to a higher energy level.
   		...an electron in that atom will move to a lower energy level.
   		...the photon will produce an emission spectrum.

3. Consider the following types of light. A photon of each type will carry a different amount of energy. Rank the answer choices from most energetic (top) to least energetic (bottom).

   It may be helpful to refer to the electromagnetic spectrum: Link to electromagnetic spectrum.

         -       1.       2.       3.       4.         

   X-ray

   
         -       1.       2.       3.       4.         

   Visible Light

   
         -       1.       2.       3.       4.         

   Infrared

   
         -       1.       2.       3.       4.         

   Microwaves

Answer 1

1) To determine the elements in stars, first plot the spectre of stars and measure the absorption wavelength. Then match this wavelength to the known atomic lines of different elements. Identifying the maximum intensity of certain wavelength and relating to some elements will lead to the information of the abundance of those elements. Basically 1 & 3 steps are sufficient to determine the element in stars.

2) When an electron absorpbs a photon, it gets excited and moves to higher energy level. Thus the complete sentence will be, “when an atom absorbs a photon , electrons in the atom will move to higher energy level.

3) The energy and frequency are related as,

where v is the frequency. From this relation we can see that higher is the frequency higher will be the energy. The frequency of the given photons will be in the order given below,

Thus the energy will be in the same order from most energetic to least energetic,