Prior to 1991, most astronomers assumed that gamma-ray bursts ...

[bclement10]

Prior to 1991, most astronomers assumed that gamma-ray bursts came from neutron stars (with accretion disks) within the Milky Way Galaxy. How do we now know that this hypothesis was wrong?
 
  A) Observations from the Compton Gamma-Ray Observatory showed that gamma-ray bursts occur too frequently to be attributed to neutron stars.
  B) Observations from the Compton Gamma-Ray Observatory showed that gamma-ray bursts come randomly from all directions in the sky.
  C) Observations from the Compton Gamma-Ray Observatory allowed us to trace gamma-ray bursts to pulsating variable stars in distant galaxies.
  D) We now know that gamma-ray bursts come not from neutron stars but from black holes.
  E) Theoretical work has proven that gamma rays cannot be produced in accretion disks.

Question 2

The most common isotope of gold has atomic number 79 and atomic mass number 197. How many protons and neutrons does the gold nucleus contain? Assuming the gold is electrically neutral, how many electrons does it have?
 
  What will be an ideal response?

[britb2u]

Answer to Question 1

B

Answer to Question 2

The most common isotope of gold contains 79 protons and 118 neutrons. If it is neutral, it also contains 79 electrons.

[bclement10]

Excellent

[momolu]

Gracias!